diff --git a/pypact/input/inputdata.py b/pypact/input/inputdata.py
index 8e00f59..a2e43f7 100644
--- a/pypact/input/inputdata.py
+++ b/pypact/input/inputdata.py
@@ -451,4 +451,10 @@ def _deserialize(self, f):
                     if num_elements == 0:
                         in_mass_section = False
                 else:
-                    raise PypactInvalidOptionException("Invalid element line format in MASS section.")
\ No newline at end of file
+                    raise PypactInvalidOptionException("Invalid element line format in MASS section.")
+
+            elif line.startswith("DENSITY"):
+                parts = line.split()
+                if len(parts) != 2:
+                    raise PypactInvalidOptionException("Invalid DENSITY line format.")
+                self.setDensity(float(parts[1]))
diff --git a/tests/input/inputfiletest.py b/tests/input/inputfiletest.py
index 7dc92db..8c7712e 100644
--- a/tests/input/inputfiletest.py
+++ b/tests/input/inputfiletest.py
@@ -27,4 +27,10 @@ def test_reading_in_mass(self):
         ]
         for i, (element, percentage) in enumerate(expected_elements):
             assert ff._inventorymass.entries[i][0] == element, f"Element {i} should be {element}"
-            assert ff._inventorymass.entries[i][1] == percentage, f"Percentage of {element} should be {percentage}"
\ No newline at end of file
+            assert ff._inventorymass.entries[i][1] == percentage, f"Percentage of {element} should be {percentage}"
+
+    def test_reading_in_density(self):
+        ff = pp.InputData()
+        pp.from_file(ff, 'reference/test.i')
+
+        assert ff._density == 19.5