Investigations were performed on 10- and 55-day-old female Wistar rats. 1 or 2 mg sodium dichromate/100 g b. m. were administered subcutaneously. Urine was collected for 1 hour at different times after dichromate injection. Total urinary protein as well as some protein fractions (high and low molecular weight proteins as well as albumin) were determined. In adult rats dose dependence of nephrotoxicity was found concerning the extent and duration of renal damage. Separation of proteins gave an insight into the location of injury. At the beginning and in the recovery phase preferentially tubular damage was found. The peak of damage is characterized by additional glomerular disturbances. Young rats are much less susceptible to dichromate than adult rats are. Possible reasons are discussed.