Purpose: This study was done to develop a web-based educational program on prevention of foot lesion in adults with diabetes and to evaluate the effects of this program on patients' knowledge of foot care, foot self-efficacy, foot self-care behavior, diabetes foot screening tool, and foot management check scores. Methods: The webbased educational program on prevention of foot lesions in adults with diabetes was developed through the process of analysis, development, implement and evaluation. Theoretical framework was derived from Bandura's Self Efficacy Theory. The research design was a non-equivalent control group pretest-posttest design. Forty-eight patients with diabetes were randomly assigned to the experimental group (24) or control group (24). Results: The finished program on prevention of foot lesion in adults with diabetes was posted at http://www.footlove.co.kr. Total scores for knowledge of foot care, foot efficacy, and foot care behavior in the experimental group were significantly higher than the control group (p<.05). Total scores for foot diabetes, foot management check score, and status of foot management in the experimental group were significantly lower than the control group (p<.05). Conclusion: These results suggest the importance of web-based diabetes foot prevention education programs to prevent foot lesions in adult patients with diabetes.