The clinical effectiveness and safety of propiverine hydrochloride (P-4, 20 mg tablet) were studied on 29 patients with nervous pollakisuria, neurogenic bladder or unstable bladder, whose chief complaints were urinary frequency and/or urinary incontinence. The clinical efficacy was "good" or better in 62.1% and "fair" or better in 86.2%. Patients' impressions were "good" or better in 79.3%. There were a total of 4 cases (13.8%) of adverse reactions, namely, two cases of decreased urinary stream, one dry mouth, and one dizziness. These reactions disappeared rapidly after the completion or discontinuance of drug administration, and therefore, did not constitute significant safety problems. The clinical efficacy in the treatment of subjective symptoms was 74.1% for diurnal pollakisuria, 50.0% for nocturnal pollakisuria, 83.3% for urinary incontinence and 69.0% for urgent feeling of micturition. For objective symptoms, P-4 increased significantly the volume of maximum desire to void (MDV); however it did not increase significantly the residual urine volume. The results of this study suggest that propiverine hydrochloride is very useful for the treatment of urinary frequency and/or incontinence.