In our study of 1400 percutaneous renal biopsies we have found a new morphological type of renal change: a nephropathy with foam cells, seen in patients without any peculiar clinical characteristics. Two cases of this nephropathy are presented with similar light microscopic changes but widely different electron microscopic findings. We interpret the differences of the electron microscopic studies to be produced by deposits of different nature. In Case 1, the deposits are osmiophilic, probably phospholipid, and of four morphological types. These types are similar to those described in Fabry's and Tay-Sachs's diseases, but in a patient without dermatological or neurological involvement. In Case 2, the deposits are cholesterol. With the electron microscope the vacuoles generally appear empty and partially osmiophilic.