Purpose: We analyzed the incidence of and risk factors for complications and conversions in a large contemporary series of patients treated with urological laparoendoscopic single site surgery. Materials and Methods: The study cohort consisted of consecutive patients treated with laparoendoscopic single site surgery between August 2007 and December 2010 at a total of 21 institutions. A logistic regression model was used to analyze the risks of conversion, and of any grade and only high grade postoperative complications. Results: Included in analysis were 1,163 cases. Intraoperatively complications occurred in 3.3% of cases. The overall conversion rate was 19.6% with 14.6%, 4% and 1.1% of procedures converted to reduced port laparoscopy, conventional laparoscopic/robotic surgery and open surgery, respectively. On multivariable analysis the factors significantly associated with the risk of conversion were oncological surgical indication (p = 0.02), pelvic surgery (p <0.001), robotic approach (p <0.001), high difficulty score (p = 0.004), extended operative time (p = 0.03) and an intraoperative complication (p = 0.001). A total of 120 postoperative complications occurred in 109 patients (9.4%) with major complications in only 2.4% of the entire cohort. Reconstructive procedure (p = 0.03), high difficulty score (p = 0.002) and extended operative time (p = 0.02) predicted high grade complications. Conclusions: Urological laparoendoscopic single site surgery can be done with a low complication rate, resembling that in laparoscopic series. The conversion rate suggests that early adopters of the technique have adhered to the principles of careful patient selection and safety. Besides facilitating future comparisons across institutions, this analysis can be useful to counsel patients on the current risks of urological laparoendoscopic single site surgery. © 2012 American Urological Association Education and Research, Inc.