diff --git a/mordred/_base/calculator.py b/mordred/_base/calculator.py
index cf713ea0..ff9486a7 100644
--- a/mordred/_base/calculator.py
+++ b/mordred/_base/calculator.py
@@ -340,9 +340,15 @@ def pandas(self, mols, nproc=None, nmols=None, quiet=False, ipynb=False, id=-1):
         """
         import pandas
 
+        if isinstance(mols, pandas.Series):
+            index = mols.index
+        else:
+            index = None
+
         return pandas.DataFrame(
             (list(r) for r in self.map(mols, nproc, nmols, quiet, ipynb, id)),
             columns=[str(d) for d in self.descriptors],
+            index=index,
         )