The study of 62 bladder neck and urethral obstructions among 210 neurogenic bladder in children, allow to give an urologic definition, corroborated by urodynamic exploration.--28 boys show lesions of external sphincer as described in traumatic paraplegia in adult. The treatment in external sphincterotomy: by perineal approach (5 cases : 1 success--4 failures), or retropubic (3 cases : 2 successes--1 failure) and mainly endoscopic (12 successes over 21 primary resections, and 8 successes over 10 repeated interventions). The results are given according to the obstruction, the continence and urinary upper tract. Ureteroneocystostomy il allowed by obstruction release. The pathogeny of obstruction is discussed according to the paralysis of the sphincter, as well as the therapy with the comparison between sphincterotomy and self-catheterism.--34 girls present 3 kinds of obstruction;--bladder neck dysectasia (5 cases) with obvious radiologic findings: YV plasty was done with in 2 cases ureteroneocystostomy;--posterior downfall of the bladder where intermittent catheterization provides excellent results;--pure urethral obstruction is also observed, like in boy's external sphincter lesion. Various types of therapy are discussed, specialy TV plasty extented to the urethral meatus, but in girls the intermittent catheterization which respects continence and which can be associated to an ureteroneocystostomy or a pharmacologic therapy is at present the most appropriate method.