diff --git a/presto-docs/src/main/sphinx/prestissimo.rst b/presto-docs/src/main/sphinx/prestissimo.rst
index 9c27b1c6412d9..259496e70f413 100644
--- a/presto-docs/src/main/sphinx/prestissimo.rst
+++ b/presto-docs/src/main/sphinx/prestissimo.rst
@@ -21,3 +21,4 @@ Prestissimo's codebase is located at `presto-native-execution
     :maxdepth: 1
 
     prestissimo/prestissimo-features
+    prestissimo/prestissimo-limitations
diff --git a/presto-docs/src/main/sphinx/prestissimo/prestissimo-limitations.rst b/presto-docs/src/main/sphinx/prestissimo/prestissimo-limitations.rst
new file mode 100644
index 0000000000000..4ce965fea739f
--- /dev/null
+++ b/presto-docs/src/main/sphinx/prestissimo/prestissimo-limitations.rst
@@ -0,0 +1,19 @@
+=======================
+Prestissimo Limitations
+=======================
+
+.. contents::
+    :local:
+    :backlinks: none
+    :depth: 1
+
+Functions
+=========
+
+reduce_agg
+----------
+
+In Prestissimo, ``reduce_agg`` is not permitted to return ``null`` in either the 
+``inputFunction`` or the ``combineFunction``. In Presto Java, this is permitted 
+but undefined behavior. For more information about ``reduce_agg`` in Presto, 
+see `reduce_agg <../functions/aggregate.html#reduce_agg>`_. 
\ No newline at end of file