A double-blind, placebo-controlled study in 20 patients with 'prostatitis syndromes' and confirmed urodynamic abnormalities using the alpha 1-receptor-blocking compound alfuzosin is reported. Flow rate recordings are probably the most reliable and useful objective variables in this type of investigation. There is a significant beneficial effect in the group using an active compound concerning maximal flow (p = 0.01), flow time (p = 0.03) and time to maximal flow (p = 0.01). However, compared with the group using a placebo, only the change in the maximal flow rate appeared to be significantly different. Subjective effects were more pronounced in the alfuzosin group, but the spurious nature of the subjective observations is stressed. Based on objective parameters, alfuzosin seems to be effective compared to placebo in the treatment of these patients with micturition complaints of an irritative nature and urodynamic abnormalities, while only minor side effects were noticed.