Male and female (840 each) BALB/cStCrlfC3Hf/Nctr mice were given 0, 7, 14, 28, 55, 110 and 220, and 0, 7, 19, 38, 75, 150 and 300 ppm, respectively, of 4-aminobiphenyl in their drinking water. Necropsies on killed animals were performed at 13, 26, 39, 52 and 96 weeks on dose. Dose-related neoplasms were angiosarcomas, bladder urothelial carcinomas and hepatocellular neoplasms. The non-neoplastic dose-related lesions were left atrial thrombosis, bladder urothelial hyperplasia, splenic hemosiderosis and splenic erythropoiesis. The incidences of bladder carcinoma and atrial thrombosis were higher in the males and the incidences of hepatocellular neoplasms and angiosarcomas were higher in the females.