Many patients are misdiagnosed as having refractory chronic nonbacterial prostatitis, and are treated with antibiotics and/or alpha-blockers with variable success. This study was designed to ascertain the potential diagnostic role of synchronous video-pressure-flow urodynamics and the therapeutic role of transurethral incision of the bladder neck in 34 consecutive men (age 26 to 51 years) with a minimum of 2 years of misdiagnosis. Duration of symptoms ranged from 25 to 126 months (mean 38.3). The average number of previous antibiotic days ranged from 42 to 136 (mean 54.3). In addition, 24 men were given empiric trials of alpha-blockers, all unsuccessful. Patients with evidence of bacterial infection or excessive leukocytes in expressed prostatic secretions were excluded from the study. Of these 34 patients 31 had urodynamic evidence of bladder outlet obstruction localized fluoroscopically to the vesical neck, while the remaining 3 had normal studies. The mean pretreatment maximum urine flow was 9.2 ml. per second and the mean maximal detrusor pressure was 76.3 cm. water. In 31 patients the bladder neck was incised at the 5 o'clock position from the bladder neck to the verumontanum with the patient under caudal (22) or spinal (9) anesthesia. Of these 31 patients 30 had marked subjective improvement in symptoms with an increase in maximal urine flow to 16.4 and 15.7 ml. per second at 3 and 6 months, respectively. The remaining patient noticed continued symptoms despite urine flow improvement. All 31 patients reported postoperative antegrade ejaculation. These results indicate that many men who are categorized as having and empirically treated for chronic nonbacterial prostatitis are misdiagnosed and, in fact, have bladder outlet obstruction. Urodynamics are helpful in diagnosing and predicting success in these patients. Furthermore, transurethral incision of the bladder neck is an effective and safe therapeutic modality in this group.