Aims: Colon perforation is the most serious complication of colonoscopy, and tends to be considered as malpractice. The aim of this study was to identify the characteristics and causes of medical accidents by analyzing lawsuit cases on colon perforation during colonoscopy. Methods: We collected judgment results that were ruled from 2005 to 2015 using the keyword of ‘colonoscopy’ in the ‘Korea’s Written Judgment Public Reading System’ of the Supreme Court, and extracted the cases of colon perforation. Characteristics of medical accidents and the decisions of courts were analyzed from written judgments. Results: Twenty-two lawsuits were analyzed. Most cases were ruled in favor of the plaintiff (n=20). The allegations against defendants, filed by the plaintiffs, were the performance error (n=22), the improper monitoring after colonoscopy (n=7), and the lack of informed consent (n=8). The median compensation was 9,335.47 US dollar, this is about 130 times the cost of a single colonoscopy in Korea. The greater the intestinal damage, the greater the amount of compensation (p=0.016). The time interval from procedure to diagnosis of perforation was most frequently 24 hours later (n=9). Conclusions: It is important to educate patients fully about the symptoms of colon perforation and to guide them to contact medical institutions immediately when symptoms occur. In addition, doctors should explain sufficiently the possibility of perforation before colonoscopy to the patients, not caregiver, and get an informed consent.