Thickening of the heel-pad is added to the list of side effects of Dilantin medication. Any measurement above 20 mm. in a white patient was considered abnormal. Only 1 of 43 controls measured above this value, while in patients receiving Dilantin the percentage of patients manifesting abnormally thickened heel-pads increased steadily with length of treatment; after 10 years 7 out of 12 patients showed this change. Dilantin medication should be included in the differential diagnosis of heel-pad thickening.