PURPOSE: We compared urinary incontinence severity measures and the impact of stress urinary incontinence in normal, overweight and obese women. MATERIALS AND METHODS: Baseline characteristics of subjects in the SISTEr (655) and the TOMUS (597) were analyzed. Body mass index was defined as normal (less than 25 kg/m(2)), overweight (25 to less than 30 kg/m(2)) and obese (30 kg/m(2) or greater). Independent urinary incontinence severity measures included a 3-day diary including incontinence episode frequency, Urogenital Distress Inventory scores and Valsalva leak point pressure from urodynamic testing. Impact was measured using the Incontinence Impact Questionnaire. Multivariable regression models were fit for each severity measure (Urogenital Distress Inventory, incontinence episode frequency, Valsalva leak point pressure and Incontinence Impact Questionnaire) on weight category. Covariates included age, race, diabetes and variables significantly associated with body mass index on bivariate analysis. RESULTS: Mean age (SD) of participants was 51.9 (10.3) in SISTEr and 52.9 (11.0) in TOMUS. In each trial 45% of subjects were obese. In SISTEr multivariable regression analyses showed that higher weight category was independently associated with higher mean Urogenital Distress Inventory score (p = 0.003), incontinence episode frequency (p <0.0001), Valsalva leak point pressure (p = 0.003) and Incontinence Impact Questionnaire score (p = 0.0004). In TOMUS higher weight category was not associated with Urogenital Distress Inventory score (p = 0.24) but was associated with higher incontinence episode frequency (p = 0.0003), Valsalva leak point pressure (p = 0.0006) and Incontinence Impact Questionnaire score (p <0.0001). CONCLUSIONS: Obese women undergoing surgery for stress urinary incontinence report more incontinence episodes, more symptom distress and worse quality of life despite better measure of urethral function (higher Valsalva leak point pressure) on urodynamics.