Neurological evaluation was performed in 24 men and 5 women with Parkinson's disease who had persistent bladder symptoms. Detrusor hyperreflexia was found in 26 (90 per cent) of the patients. Sporadic involuntary electromyography activity of the external sphincter during involuntary detrusor contractions was encountered in 61 per cent but in none did this cause obstruction. Coordinated striated sphincter relaxation during voluntary detrusor contraction was found in 13 patients (45 per cent). Among 22 men who were in the prostatic disease age group only 4 (18 per cent) had definite prostatic obstruction. Moreover, none of 8 men with persistent symptoms after prostatectomy had evidence of bladder outlet obstruction.