diff --git a/smithy-aws-protocol-tests/model/restJson1/http-content-type.smithy b/smithy-aws-protocol-tests/model/restJson1/http-content-type.smithy
new file mode 100644
index 00000000000..041f4f34046
--- /dev/null
+++ b/smithy-aws-protocol-tests/model/restJson1/http-content-type.smithy
@@ -0,0 +1,291 @@
+// This file defines test cases that test both the HTTP body
+// and content-type handling.
+
+$version: "1.0"
+
+namespace aws.protocoltests.restjson
+
+use aws.protocols#restJson1
+use aws.protocoltests.shared#TextPlainBlob
+use smithy.test#httpRequestTests
+use smithy.test#httpResponseTests
+
+/// This example operation serializes a structure in the HTTP body.
+///
+/// It should ensure Content-Type: application/json is
+/// used in all requests and that an "empty" body is
+/// an empty JSON document ({}).
+///
+@idempotent
+@http(uri: "/body", method: "POST")
+operation TestBodyStructure {
+    input: TestBodyStructureInputOutput,
+    output: TestBodyStructureInputOutput
+}
+
+apply TestBodyStructure @httpRequestTests([
+    {
+        id: "RestJsonTestBodyStructure",
+        documentation: "Serializes a structure",
+        protocol: restJson1,
+        method: "POST",
+        uri: "/body",
+        body: """
+              {"testConfig":
+                  {"timeout": 10}
+              }""",
+        bodyMediaType: "application/json",
+        headers: {
+            "Content-Type": "application/json"
+        },
+        requireHeaders: [
+            "Content-Length"
+        ],
+        params: {
+            testConfig: {
+                timeout: 10,
+            }
+        }
+    }
+])
+
+apply TestBodyStructure @httpRequestTests([
+    {
+        id: "RestJsonHttpWithEmptyBody",
+        documentation: "Serializes an empty structure in the body",
+        protocol: restJson1,
+        method: "POST",
+        uri: "/body",
+        body: "{}",
+        bodyMediaType: "application/json",
+        headers: {
+            "Content-Type": "application/json"
+        },
+        requireHeaders: [
+            "Content-Length"
+        ],
+        params: {}
+    }
+])
+
+structure TestBodyStructureInputOutput {
+    @httpHeader("x-amz-test-id")
+    testId: String,
+
+    testConfig: TestConfig
+}
+
+structure TestConfig {
+    timeout: Integer
+}
+
+/// This example operation serializes a payload targeting a structure.
+///
+/// This enforces the same requirements as TestBodyStructure
+/// but with the body specified by the @httpPayload trait.
+///
+@idempotent
+@http(uri: "/payload", method: "POST")
+operation TestPayloadStructure {
+    input: TestPayloadStructureInputOutput,
+    output: TestPayloadStructureInputOutput
+}
+
+apply TestPayloadStructure @httpRequestTests([
+    {
+        id: "RestJsonHttpWithEmptyStructurePayload",
+        documentation: "Serializes a payload targeting an empty structure",
+        protocol: restJson1,
+        method: "POST",
+        uri: "/payload",
+        body: "{}",
+        bodyMediaType: "application/json",
+        headers: {
+            "Content-Type": "application/json"
+        },
+        requireHeaders: [
+            "Content-Length"
+        ],
+        params: {}
+    }
+])
+
+apply TestPayloadStructure @httpRequestTests([
+    {
+        id: "RestJsonTestPayloadStructure",
+        documentation: "Serializes a payload targeting a structure",
+        protocol: restJson1,
+        method: "POST",
+        uri: "/payload",
+        body: """
+              {"data": 25
+              }""",
+        bodyMediaType: "application/json",
+        headers: {
+            "Content-Type": "application/json"
+        },
+        requireHeaders: [
+            "Content-Length"
+        ],
+        params: {
+            testId: "t-12345",
+            payloadConfig: {
+                data: 25,
+            }
+        }
+    }
+])
+
+apply TestPayloadStructure @httpRequestTests([
+    {
+        id: "RestJsonHttpWithHeadersButNoPayload",
+        documentation: "Serializes an request with header members but no payload",
+        protocol: restJson1,
+        method: "POST",
+        uri: "/body",
+        body: "{}",
+        bodyMediaType: "application/json",
+        headers: {
+            "Content-Type": "application/json"
+        },
+        requireHeaders: [
+            "Content-Length"
+        ],
+        params: {
+            testId: "t-12345"
+        }
+    }
+])
+
+structure TestPayloadStructureInputOutput {
+    @httpHeader("x-amz-test-id")
+    testId: String,
+
+    @httpPayload
+    payloadConfig: PayloadConfig
+}
+
+structure PayloadConfig {
+    data: Integer
+}
+
+/// This example operation serializes a payload targeting a blob.
+///
+/// The Blob shape is not structured content and we cannot
+/// make assumptions about what data will be sent. This test ensures
+/// only a generic "Content-Type: application/octet-stream" header
+/// is used, and that we are not treating an empty body as an
+/// empty JSON document.
+///
+@idempotent
+@http(uri: "/blob_payload", method: "POST")
+operation TestPayloadBlob {
+    input: TestPayloadBlobInputOutput,
+    output: TestPayloadBlobInputOutput
+}
+
+apply TestPayloadBlob @httpRequestTests([
+    {
+        id: "RestJsonHttpWithEmptyBlobPayload",
+        documentation: "Serializes a payload targeting an empty blob",
+        protocol: restJson1,
+        method: "POST",
+        uri: "/blob_payload",
+        body: "",
+        bodyMediaType: "application/octet-stream",
+        headers: {
+            "Content-Type": "application/octet-stream"
+        },
+        requireHeaders: [
+            "Content-Length"
+        ],
+        params: {}
+    }
+])
+
+apply TestPayloadBlob @httpRequestTests([
+    {
+        id: "RestJsonTestPayloadBlob",
+        documentation: "Serializes a payload targeting a blob",
+        protocol: restJson1,
+        method: "POST",
+        uri: "/payload_blob",
+        body: """
+              1234
+              """,
+        bodyMediaType: "image/jpg",
+        headers: {
+            "Content-Type": "image/jpg"
+        },
+        requireHeaders: [
+            "Content-Length"
+        ],
+        params: {
+            contentType: "image/jpg",
+            data: "1234"
+        }
+    }
+])
+
+structure TestPayloadBlobInputOutput {
+    @httpHeader("Content-Type")
+    contentType: String,
+
+    @httpPayload
+    data: Blob
+}
+
+/// This example operation serializes a request without an HTTP body.
+///
+/// These tests are to ensure we do not attach a body or related headers
+/// (Content-Length, Content-Type) to operations that semantically
+/// cannot produce an HTTP body.
+///
+@readonly
+@http(uri: "/no_payload", method: "GET")
+operation TestNoPayload {
+    input: TestNoPayloadInputOutput,
+    output: TestNoPayloadInputOutput
+}
+
+apply TestNoPayload @httpRequestTests([
+    {
+        id: "RestJsonHttpWithNoModeledBody",
+        documentation: "Serializes a GET request with no modeled body",
+        protocol: restJson1,
+        method: "GET",
+        uri: "/no_payload",
+        body: "",
+        forbidHeaders: [
+            "Content-Length",
+            "Content-Type"
+        ],
+        params: {}
+    }
+])
+
+apply TestNoPayload @httpRequestTests([
+    {
+        id: "RestJsonHttpWithHeaderMemberNoModeledBody",
+        documentation: "Serializes a GET request with header member but no modeled body",
+        protocol: restJson1,
+        method: "GET",
+        uri: "/no_payload",
+        body: "",
+        headers: {
+            "X-Amz-Test-Id": "t-12345"
+        },
+        forbidHeaders: [
+            "Content-Length",
+            "Content-Type"
+        ],
+        params: {
+            testId: "t-12345"
+        }
+    }
+])
+
+structure TestNoPayloadInputOutput {
+    @httpHeader("X-Amz-Test-Id")
+    testId: String,
+}
diff --git a/smithy-aws-protocol-tests/model/restJson1/main.smithy b/smithy-aws-protocol-tests/model/restJson1/main.smithy
index c81aa78a27c..070f29e6cbd 100644
--- a/smithy-aws-protocol-tests/model/restJson1/main.smithy
+++ b/smithy-aws-protocol-tests/model/restJson1/main.smithy
@@ -127,5 +127,11 @@ service RestJson {
         MalformedAcceptWithBody,
         MalformedAcceptWithPayload,
         MalformedAcceptWithGenericString,
+
+        // request body and content-type handling
+        TestBodyStructure,
+        TestPayloadStructure,
+        TestPayloadBlob,
+        TestNoPayload,
     ]
 }