The necessity for additional animal models for prostate cancer has recently been stressed. The Pollard model of chemically induced prostate cancer has received attention in this regard although the histiogenetic origin of these tumors has come under question. We independently studied this model for the development of tumors in the prostate region. The tumors, all of which were adenocarcinomas, first became grossly evident 5 months after induction and ultimately occurred in 71% of the animals. Seventy-three % of the tumors involved only the seminal vesicle, 22% involved other portions of the prostatic complex as well as the seminal vesicle, and 5% were located in the coagulating gland (anterior prostate). Although the majority of tumors arose in or involved the seminal vesicle, this may still be a useful model for the study of human prostate cancer because the tumors are adenocarcinomas, occur in the large majority of animals, are hormonally induced, and have the propensity to metastasize.