diff --git a/openfermionpyscf/_run_pyscf.py b/openfermionpyscf/_run_pyscf.py
index b374b2c..997e545 100644
--- a/openfermionpyscf/_run_pyscf.py
+++ b/openfermionpyscf/_run_pyscf.py
@@ -103,9 +103,9 @@ def run_pyscf(molecule,
               run_cisd=False,
               run_ccsd=False,
               run_fci=False,
-              verbose=False):
-    """
-    This function runs a pyscf calculation.
+              verbose=False,
+              save=True):
+    """This function runs a pyscf calculation.
 
     Args:
         molecule: An instance of the MolecularData or PyscfMolecularData class.
@@ -115,6 +115,7 @@ def run_pyscf(molecule,
         run_ccsd: Optional boolean to run CCSD calculation.
         run_fci: Optional boolean to FCI calculation.
         verbose: Boolean whether to print calculation results to screen.
+        save: Boolean whether to save the calculated molecular data to disk.
 
     Returns:
         molecule: The updated PyscfMolecularData object. Note the attributes
@@ -202,7 +203,8 @@ def run_pyscf(molecule,
     # Return updated molecule instance.
     pyscf_molecular_data = PyscfMolecularData.__new__(PyscfMolecularData)
     pyscf_molecular_data.__dict__.update(molecule.__dict__)
-    pyscf_molecular_data.save()
+    if save:
+        pyscf_molecular_data.save()
     return pyscf_molecular_data
 
 
diff --git a/openfermionpyscf/tests/_run_pyscf_test.py b/openfermionpyscf/tests/_run_pyscf_test.py
index 3481d23..a7083a7 100644
--- a/openfermionpyscf/tests/_run_pyscf_test.py
+++ b/openfermionpyscf/tests/_run_pyscf_test.py
@@ -13,6 +13,8 @@
 """Tests many modules to call pyscf functions."""
 from __future__ import absolute_import
 
+import os
+
 from openfermion.chem import MolecularData
 from openfermionpyscf import run_pyscf
 from openfermionpyscf import PyscfMolecularData
@@ -37,3 +39,22 @@ def test_run_pyscf():
                          run_fci=True,
                          verbose=1)
     assert isinstance(new_mole, PyscfMolecularData)
+
+
+def test_run_pyscf_without_save(tmp_path):
+    test_molecule = MolecularData(geometry,
+                                  basis,
+                                  multiplicity,
+                                  charge,
+                                  data_directory=str(tmp_path))
+
+    new_mole = run_pyscf(test_molecule,
+                         run_scf=True,
+                         save=False)
+    assert isinstance(new_mole, PyscfMolecularData)
+    assert not os.path.exists(f'{new_mole.filename}.hdf5')
+
+    new_mole_saved = run_pyscf(test_molecule,
+                               run_scf=True)
+    assert isinstance(new_mole_saved, PyscfMolecularData)
+    assert os.path.exists(f'{new_mole_saved.filename}.hdf5')