Bladder outlet obstruction in women is a rare entitiy, and difficult to diagnose. In our series most of the patients had previous history of gyneco-obstetric or urological procedures. Cystometry enabled us to diagnose the coexistence of bladder instability and obstruction in 38 % of the patients. We did not find statistically significant differences between the patients with and without BI in terms of degree of obstruction measured by uroflowmetry and pressure/flow studies. Pressure/flow studies and Uroflowmetry had been the essential key in the diagnosis of obstruction in our series. Cysto-urethrography and urethroscopy were normal in over 50 % of patients. The urethral calibration was abnormal in 16 % of the cases.