Purpose: The purpose of this study was to evaluate the effects of an educational video program on bowel preparation for acolonoscopy. Methods: The study used a non-equivalent control group and non-synchronized design as a quasi-experimental researchinvolving 101 participants undergoing bowel preparation for a colonoscopy (experimental group 51, control group 50 subjects)at W. university hospital, from Aug. 7 to Oct. 31, 2013. The control group received verbal education with an explanatory notewhile the experimental group received education using a video program. To measure knowledge of diet restrictions and compliancewith ingesting bowel preparation solutions, a questionnaire, based on The Korean Society of Gastrointestinal Endoscopy’s Guide(2003), developed by Sam-Sook You, was used after revisions and supplementation was done. To measure bowel cleanness, the‘Aronchick Bowel Preparation Scale’ was adopted. Data were analyzed using the SPSS WIN 12.0 program. Results: A higher proportionof the experimental group showed a positive change in knowledge level on diet restrictions (U=1011.50, p =.035) and ingestionof bowel preparation solutions (U=980.50, p =.019), a higher level of compliance with diet restrictions (U=638.50, p qqqlt;.001), ingestingbowel preparation solutions (U=668.00, p qqqlt;.001) and the level of bowel cleanness (χ 2=17.00, p qqqlt;.001) than the control group. Conclusion:The results of this study indicate that a video educational program for patients having a colonoscopy can improve knowledge,level of compliance with diet restrictions, ingestion of bowel preparation solutions, and bowel cleanness. Therefore video educationalprogram should be used with this patient group.