Male and female BDVI rats were treated with 1 mmol/kg x week and 0.5 mmol/kg x week of N-nitrodimethylamine (NTDMA) or N-nitromethylamine (NTMA). NTMA induced mainly tumors of the nasal cavity (esthesioneuro-epithelioma) while NTMA induced neurinoma of the spine, spinal nerves and peripheral nerves. NTMA was slightly less potent than the dimethyl compound. Females were less susceptible than males to the carcinogenic action of the nitramines.