Colonoscopy remains the gold standard for colorectal cancer screening. Many barriers to the procedure exist including the possibility of abdominal discomfort that may occur with insufflation. Carbon dioxide (CO2), which is rapidly absorbed in the blood stream, is an alternate method used to distend the lumen during colonoscopy. The goal of this study was to compare patient discomfort, abdominal girth, and recovery time in 2 groups of patients randomized to CO2 versus room air insufflation during colonoscopy. Using a Wong–Baker score, we found statistical difference in postprocedural discomfort levels (CO2 Group: 1.15 ± 2.0 vs. room air: 0.41 ± 0.31, p = .015) and a significantly greater increase in abdominal girth over CO2 immediately postprocedure (room air: 1.06 ± 1.29 inches vs. CO2: 0.56 ± 0.73 inches, p = .054) girth immediately postprocedure; however, recovery time was similar between the 2 study arms (CO2: 9.1 ± 16.2 minutes vs. room air: 10.2 ± 18.6 minutes, p = .713). Further studies are needed to determine whether CO2 is cost-effective and improves patient satisfaction with colonoscopy.