N-nitrosomethylurea (NMU, 20 mg/kg) was administered to rats intraperitoneally on the 21st day of pregnancy. F1 progeny aged 3 months showed a decrease in glucose utilization and in somatomerin content as measured by the glucose tolerance test. The insulin serum level did not differ from control. The cholesterol blood level was higher in the offspring of NMU-treated rats. The ability of diethylstilbestrol to inhibit the compensatory ovarian hypertrophy was decreased in 3-month-old female hemicastrated rats whose mothers had been exposed to NMU. Administration of the antidiabetic drug buformin decreased 3.5-fold the malignant neurogenic tumor incidence in rats transplacentally treated with NMU.