INTRODUCTION AND HYPOTHESIS: The purpose of this study is to describe risk factors for post-operative urinary tract infection (UTI) the first year after stress urinary incontinence surgery. METHODS: Multivariable logistic regression analyses were performed on data from 1,252 women randomized in two surgical trials, Stress Incontinence Surgical Treatment Efficacy trial (SISTEr) and Trial Of Mid-Urethral Slings (TOMUS). RESULTS: Baseline recurrent UTI (rUTI; ≥3 in 12 months) increased the risk of UTI in the first 6 weeks in both study populations, as did sling procedure and self-catheterization in SISTEr, and bladder perforation in TOMUS. Baseline rUTI, UTI in the first 6 weeks, and PVR > 100 cc at 12 months were independent risk factors for UTI between 6 weeks and 12 months in the SISTEr population. Few (2.3-2.4%) had post-operative rUTI, precluding multivariable analysis. In women with pre-operative rUTI, successful surgery (negative cough stress test) at 1 year did not appear to decrease the risk of persistent rUTI. CONCLUSIONS: Pre-operative rUTI is the strongest risk factor for post-operative UTI.