OBJECTIVE We describe the presentation, clinical characteristics, treatment and followup of a series of women with primary bladder neck obstruction (PBNO). METHODS A patient data base was searched for women who underwent transurethral resection for bladder outlet obstruction diagnosed by videourodynamic study (VUDS) according to the Blaivas-Groutz nomogram for female bladder outlet obstruction between 1993 and 2002. A total of 37 women with obstruction were identified. Patients with neurogenic, traumatic, anatomical or iatrogenic causes of obstruction were excluded. Seven patients remained who had been diagnosed with PBNO, of whom all underwent transurethral bladder neck resection. Office records were reviewed for history, presentation, surgical treatment and clinical outcome. RESULTS Seven patients were diagnosed with PBNO. Age was 39 to 81 years. Six of 7 patients presented with symptoms of obstruction, including a weak or intermittent stream and urinary hesitancy. These 6 patients had unremarkable physical examination findings with normal perianal sensation, anal sphincter tone and lower extremity reflexes. One patient presented with abdominal swelling, which on physical examination was found to be a markedly distended bladder containing more than 1000 cc urine. All patients had overt urethral obstruction on VUDS. In 6 of 7 patients obstruction was clearly at the vesical neck and in 1 the obstruction site was equivocal. Three patients were treated or had previously been treated pharmacologically with alpha-blockers. All patients were subsequently treated with intermittent self-catheterization. All patients then underwent transurethral bladder neck resection at the vesical neck and proximal urethra. Surgical specimens weighed 1 to 5 gm and showed urethral fragments or fibromuscular tissue without specific pathological findings. Followup was 1 to 10 years (median 3) and it included physical examination, uroflowmetry, post-void residual urine measurement and videourodynamic study. Six patients considered themselves cured of lower urinary tract symptoms and 1 was improved. In 1 patient the obstruction site was not clear. One patient had mild stress incontinence under rare circumstances not severe enough to require protective pads. The average change in flow was 6 +/- 10 vs 30 +/- 17 ml per second (p <0.03). The average change in voided volume was 194 +/- 170 vs 416 +/- 206 ml per second (p <0.06). Average change in post-void residual urine was 680 +/- 445 vs 173 +/- 366 ml (p <0.05). CONCLUSIONS PBNO is an exceedingly rare condition, which is easily treatable when properly diagnosed by VUDS. The presentation of patients in urinary retention in middle age suggests that PBNO may be more common in less apparent forms than has previously been recognized.