diff --git a/utils/metrics/RefUniqueGram.py b/utils/metrics/RefUniqueGram.py
new file mode 100644
index 0000000..5da0f4b
--- /dev/null
+++ b/utils/metrics/RefUniqueGram.py
@@ -0,0 +1,75 @@
+import nltk
+from utils.metrics.Metrics import Metrics
+from nltk import ngrams
+
+class RefUniqueGram(Metrics):
+    def __init__(self, test_text='',ref_text='', gram=3):
+        super().__init__()
+        self.name = 'RefUniqueGram'
+        self.test_data = test_text
+        self.ref_data=ref_text
+        self.gram = gram
+        self.sample_size = 500
+        self.test_text=None
+        self.reference_text = None
+        self.is_first = True
+    
+    def get_score(self, ignore=False):
+        if ignore:
+            return 0
+        if self.is_first:
+            self.get_reference()
+            self.get_test()
+            self.is_first = False
+        return self.get_ng()
+
+    def get_ng(self):
+        documentRef = self.get_reference()
+        documentTest= self.get_test()
+        length = len(documentTest) 
+        gramsRef = list()
+        gramsTest = list()
+        for sentence in documentRef:
+            gramsRef += self.get_gram(sentence)
+        
+        for sentence in documentTest:
+            gramsTest += self.get_gram(sentence)
+        
+
+        return len(set(gramsTest).difference(set(gramsRef)))/length
+
+    def get_gram(self, tokens):
+        grams = list()
+        if len(tokens) < self.gram:
+            return grams
+        gram_generator = ngrams(tokens, self.gram)
+        for gram in gram_generator:
+            grams.append(gram)
+        return grams
+
+
+    def get_reference(self):
+        if self.reference_text is None:
+            reference = list()
+            with open(self.ref_data) as ref_text:
+                for text in ref_text:
+                    #text = text.strip().split(" ")
+                    text= nltk.word_tokenize(text)
+                    reference.append(text)
+            self.reference_text = reference
+            return reference
+        else:
+            return self.reference_text
+
+    def get_test(self): 
+        if self.test_text is None:
+            test = list()
+            with open(self.test_data) as test_text:
+                for text in test_text:
+                    text = nltk.word_tokenize(text)
+                    test.append(text)
+            self.test_text = test
+            return test
+        else:
+            return self.test_text
+