Bladder function in patients with posterior urethral valves (PUV) has an immense impact on long-term continence and renal function. Bladder dysfunction was corelated with the initial surgical treatment in 67 patients with PUV treated between 1985 and 2000. Age at presentation, current age, duration of follow-up, initial surgical treatment (diversion or valve fulguration), trends of renal function tests, voiding disturbances, and changes in the upper tracts were recorded. Urodynamic studies were done in all patients to determine urine flow rates, residual volume, maximal cystometric capacity (MCC), bladder compliance, involuntary detrusor activity, and pressure-specific bladder volume (PSBV) at 30 cm water. The patients were divided into three groups depending on the initial treatment: fulguration (n = 38), vesicostomy (n = 25), and ureterostomy (n = 4). At the time of this study voiding symptoms persisted in 45 patients. Mean percent MCC (% MCC) was 62%, 96%, and 100% of normal in the vesicostomy, fulguration, and ureterostomy groups, respectively (P = 0.002). Large-capacity bladders were seen in 10.9% of patients, mostly in pubertal and post-pubertal boys who were treated initially by either fulguration or ureterostomy; vesicostomy adversely affected bladder capacity and compliance (P = 0.007). PSBV was decreased in 48% of patients in the vesicostomy group and was significantly lower in the other groups (P = 0.01). Mean percent PSBV was 75%, 95%, and 96% of normal in the vesicostomy, fulguration, and ureterostomy groups, respectively. Uninhibited contractions were present in 21 patients (14 in the vesicostomy group) (P = 0.01). The highest incidence of upper-tract deterioration was seen with %MCC below 60% of normal (P = 0.001). The predominant urodynamic patterns were: (1) fulgurated group: good-capacity, compliant bladder; (2) vesicostomy group: small-capacity, hyperreflexic bladder; and (3) ureterostomy group: good capacity, compliant bladder. Primary valve ablation is associated with better bladder function than vesicostomy and should be the treatment of choice in PUV. Also, vesicostomy and ureterostomy have distinctly different effects on bladder function.