Objective To investigate the detrusor dysfuction resulted from BPH after prostatectomy. Methods Bladder detrusor function of 114 patients were evaluated by urodynamic studies both before and after prostatectomy. Results Detrusor dysfunction and its symptoms recovered progressively after operation. Qmax after operation was (10.2?2.8)ml/s, higher than before which was (5.5?2.1)ml/s( P