Male and female Wistar rats (5-105-day-old) were administered 3 different doses of cisplatinum (CP) (0.15, 0.3 or 0.6 mg/100 g body wt, intraperitoneally) After 3 days the renal excretory functions were investigated. There were no sex differences in nephrotoxicity. In rats of all age groups a dose dependent decrease in body weight appeared. In 5- and 33-105-day-old rats the 2 lower doses did not or only mildly influence renal function. 0.6 mg CP/100 g body wt in these age groups lead to a significant reduction in urine volume. The excretion of osmotically active substances and p-aminohippurate were reduced. There is a statistically significant proteinuria. In 10- and 15-day-old rats the 2 lower doses were without any pathologic consequences, but 0.6 mg CP/100 g body wt was followed by a significant increase in the protein excretion of 15-day-old rats. Consequently, regarding the parameters measured 10-15-day-old rats seemed to be less susceptible to CP-nephrotoxicity.