The oncogenic action of carcinogenic aminoazo compounds (orthoaminoazotoluene and 4-dimethylaminoazobenzene) and cyclic amines (orthotolidine and 3,3′-dichlorobenzidine) was manifested in the progeny of BALB/c mice as a statistically significant increase in the frequency of all tumors in the progeny of the experimental animals compared with those of the control mice. After administration of the carcinogens tumors appeared in new situations, notably leukemias and liver tumors. As a result of the action of noncarcinogenic analogues from the group of aminoazo compounds (para-aminoazotoluene and diethylaminoazobenzene) no significant differences were observed between the progenies of the experimental and control group.