Seven human prostate tumor models were established by transplanting tumor fragments in NMRI athymic nude mice. Once established, the tumors were serially transplantable in both NMRI and BALB/c nude mice. The xenografts originated from primary prostatic carcinomas (prostatectomy specimens), transurethral resection material, and metastatic lesions (pelvic lymph nodes and scrotal skin). Histological examination revealed that, in the course of several mouse passages (8 to 23), tumors retained their resemblance to the original patient material. The PC-295, PC-310, PC-329, and PC-346 tumors are dependent on androgens for their growth. The PC-324, PC-339, and PC-374 tumors are androgen independent, although growth of PC-374 tumors still seemed androgen sensitive. All tumors are diploid, except for the PC-374, which is tetraploid. The diploid PC-295 tumor has an additional small population of tetraploid cells. All xenografts displayed a heterogeneous expression pattern of the androgen receptor except for the PC-324 and PC-339 tumors in which the androgen receptor could not be detected. Prostatic acid phosphatase and prostate-specific antigen were retained during serial transplantation in all tumors but the PC-324 and PC-339. This panel of permanent human prostate tumor models comprises tumors representing both the androgen-dependent and -independent stages of human prostate cancer with various degrees of differentiation and, therefore, is of great value for the study of many aspects of growth and progression of human prostate cancer.