The aim of this study was to evaluate the effect of weight reduction on urinary incontinence in moderately obese women. This prospective cohort study enrolled moderately obese women experiencing four or more incontinence episodes per week. BMI and a 7-day urinary diary were collected at baseline and on the completion of weight reduction. The study included 10 women with a mean (+/-SD) baseline BMI of 38.3 (+/-10.1) kg/m2 and 13 (+/-10) incontinent episodes per week. Participants had a mean BMI reduction of 5.3 (+/-6.2) kg/ m2 (P < 0.03). Among women achieving a weight loss of > or = 5%, 6/6 had > or = 50% reduction in incontinence frequency compared to 1 in 4 women with < 5% weight loss (P < 0.03). Incontinence episodes decreased to 8 (+/-10) per week following weight reduction (P < 0.07). The study demonstrated an association between weight reduction and improved urinary incontinence. Weight reduction should be considered for moderately obese women as part of non-surgical therapy for incontinence.