The Zoladex (ICI 118,630) multicenter trial included 149 patients with stage B +o D prostatic cancer recruited from 1984 to date. Of them 53 clinical responders on the treatment for 40 weeks or longer were subjected to assessment of antitumour response, overall subjective response, endocrinological response, safety and usefulness. The responders consistently showed a clinical response as evidenced by antitumour response in 32 of 50 patients (64.0%) at week 12 and in 35 of 51 (68.6%) at week 40, and overall subjective response in 42 out of 47 patients (89.4%) at both week 12 and week 40. Endocrinologically, all of the 47 eligible patients maintained a 40-week or longer response. Adverse reactions were observed in 19 out of 73 patients (26.0%), subdivided by the time of occurrence as 15/73 (20.5%) up to week 12, 3/71 (4.6%) between week 12 and week 40, and 5/53 (9.4%) in and after week 40. No patient required the discontinuance of treatment. Usefulness of the drug was observed in 51 out of 52 patients (98.1%). The results indicated that Zoladex in a once monthly regimen may be of great advantage to elderly patients with prostatic cancer, and allow an improved patient compliance: Zoladex may not only produce clinical remission but also improve the quality of life.