A single dose of cadmium chloride (3.23 mumol Cd2+/kg) causing acute testicular damage in male rats also caused significant creatinuria and creatinaemia at 48 h after dosing. Doses of cadmium which did not cause testicular necrosis did not cause creatinuria or creatinaemia. Surgical ligation of the pampiniform plexus also caused ischaemic necrosis of the testis and this was followed by significant creatinuria and creatinaemia. However, neither orchidectomy followed by a toxic dose of cadmium, orchidectomy alone nor sham operation caused significant creatinuria or creatinaemia. Cadmium dosing induced a temporary loss of body weight which was less than that caused by food restriction. Food restriction did not cause significant creatinuria but did cause significant creatinaemia. These data suggest that the creatine is derived from the damaged testis and that measurement of urinary creatine may be a useful non-invasive means of detecting acute testicular damage caused by exposure to chemicals or mechanical impairment of blood flow.