PURPOSE: We determined whether urinary leakage in some circumstances is associated with intrinsic sphincter deficiency, defined by a low maximum urethral closure pressure of 30 cm H(2)O or less, in women presenting for urinary incontinence. MATERIALS AND METHODS: We retrospective analyzed the records of 100 consecutive women who underwent complete urodynamic evaluations for complaints of urinary leakage. RESULTS: Logistic regression adjusted for age showed that leakage while running or during physical exertion, leakage while walking and leakage with no obvious reason were associated with intrinsic sphincter deficiency, while leakage upon coughing or sneezing was not. CONCLUSIONS: These results suggest that different mechanisms may govern incontinence during prolonged vs brief stress. Low maximum urethral closure pressure may be a sign of abnormal sphincter fatigability.