Subjective quality-of-life assessments obtained from investigators and patients were compared in a subset of 76 patients from an EORTC study (protocol 30853) on metastatic prostatic carcinoma. In this study the therapeutic effect of orchiectomy was compared with a luteinizing hormone-releasing hormone analogue depot preparation and flutamide in 327 patients in total. Pretreatment, 6- and 12-month quality-of-life assessments revealed large variations between the patients’ and the investigators’ evaluation of performance status and sexual status (potency). Correlation analysis showed that reduced social life, impaired sexual potency and fatigue played important roles in overall psychological well-being. It was concluded that quality-of-life assessments obtained by self-administration questionnaires is a feasible approach and provides a tool to evaluate the benefits of treatment in prostate cancer.