During a control campaign connected to our main program on early diagnosis of prostatic carcinoma through tissue culture of prostatic fluid samples obtained after prostatic massage (M. Bologna et al., Eur. Urol., 14, 474-476, 1988), we isolated and characterized a human prostatic carcinoma cell strain from a 58-year-old patient with a grade III prostatic carcinoma. The epithelial cell strain, named PMU-23, has been passaged in vitro for 31 subculture cycles during a period of approximately 8 months, after which cell proliferation slowed down irreversibly. The isolation of this cell strain constitutes a renewed confirmation of the validity of our method for the early diagnosis of prostatic carcinoma and demonstrates some intermediate features in the progression of prostatic tumors. In addition, the study of limited-lifespan tumor cell strains in culture may extend the knowledge on prostatic cell biology, particularly toward the identification of intermediate steps of tumor progression, for a better approach of tumor therapy and prevention of metastatic spread.