© 2015 Société Internationale de Chirurgie. Introduction: The utilization of laparoscopy in colorectal surgery is increasing. However, conversion to open surgery remains relatively high. Objective: We evaluated (1) conversion rates in laparoscopic colorectal surgery; (2) the outcomes of converted cases compared with successful laparoscopic and open colorectal operations; (3) predictive risk factors of conversion of laparoscopic colorectal surgery to open surgery. Methods: Using the National Inpatient Sample database, we examined the clinical data of patients who underwent colon and rectal resection from 2009 to 2010. Multivariate regression analysis was performed to identify factors predictive for conversion of laparoscopic to open operation. Results: A total of 207,311 patients underwent intended laparoscopic colorectal resection during this period. The conversion rate was 16.6 %. Considering resection type and pathology, the highest conversion rates were observed in proctectomy (31.4 %) and Crohn's disease (20.2 %). Using multivariate regression analysis, Crohn's disease (adjusted odds ratio [AOR], 2.80), prior abdominal surgery (AOR, 2.45), proctectomy (AOR, 2.42), malignant pathology (AOR, 1.90), emergent surgery (AOR, 1.82), obesity (AOR, 1.63), and ulcerative colitis (AOR, 1.60) significantly impacted the risk of conversion. Compared with patients who were successfully completed laparoscopically, converted patients had a significantly higher complication rate (laparoscopic: 23 %; vs. converted: 35.2 % vs. open: 35.3 %), a higher in-hospital mortality rate (laparoscopic: 0.5 %; vs. converted: 0.6 %; vs. open: 1.7 %) and a longer mean hospital stay (laparoscopic: 5.4 days; vs. converted: 8.1 days; vs. open: 8.4 days); however, converted patients had better outcomes compared with the open group. Conclusions: The conversion rate in colorectal surgery was 16.6 %. Converted patients had significantly higher rates of morbidity and mortality compared to successfully completed laparoscopic cases, although lower than open cases. Crohn's disease, prior abdominal surgery, and proctectomy are the strongest predictors for conversion of laparoscopic to open in colorectal operations.