A questionnaire consisting of 36 questions based on a visual analogue scale for measuring the quality of life (QOL) of benign prostatic hyperplasia (BPH) patients is presented and assessed. The sensitivity of the questionnaire is demonstrated by its ability to register a statistically significant (p less than 0.01) improvement of QOL after prostate surgery (transurethral resection of the prostate). Its reliability is shown by its ability to give reproducible results in a nonoperated BPH patient group. Patient compliance has been excellent. It is discussed to what extent questions directly concerning symptoms from prostatism should be included in QOL questionnaires for BPH patients. Nonparametric statistics are applied. It is concluded that questionnaires like this are useful tools in the assessment of BPH patients, irrespective of the treatment modality. They will probably be of particular value in studies of drug therapy of BPH, complementing methods of assessment like symptom score and urodynamic parameters.