Sedation-related colonoscopic perforation (CP) has been under much debate. Our aim was to assess and compare the CP rate during colonoscopy by using sedation with or without propofol adjuvant. All patients who underwent colonoscopic procedure at the WGO Endoscopy Training Center, Siriraj Hospital, Thailand from March 2005 to October 2007 by using the intravenous sedation (IVS) technique were analyzed. The primary outcome was the CP rate; the secondary outcomes were sedation-related complications and death during and immediately after the procedure. There were 6140 colonos-copies and 1532 flexible sigmoidoscopies during the study period, of which 6122 colonoscopic procedures were performed by using IVS. All of these procedures were categorized into two groups: group A, the IVS technique was propofol-based sedation and group B, the IVS technique was non-propofol-based sedation. After matching the indications of procedure, there were 2022 colonoscopies in group A and 512 colonoscopies in group B. Colonoscopic procedures were performed by staff endoscopists (10.8%) or residents and fellows (89.2%). The characteristics of patients and sedative agents used in perforated patients in both groups were not significantly different. In group A, five patients (0.25%) suffered from perforation and two of them died. In group B, one patient (0.20%) had CP; the difference was not significant (P=0.829). Our data showed that colonoscopy under propofol-based sedation did not increase the perforation rate. Serious complications are uncommon.