The purpose of this study was to develop a Web-based nutritional management program for the prevention of metabolic syndrome and to evaluate how the program affects health-related behaviors and the health status of office workers with metabolic syndrome risk factors. For the pilot test of the Web-based nutritional management program, 29 employees (19 males, 10 females) with more than one metabolic syndrome risk factor participated in the Web-based nutritional management program for 16 weeks. Participants visited the Web site more than two times per week and completed customized assessments of health status, smoking habits, alcohol consumption, dietary habits, food intake, ideal body weight, energy requirements, and exercise. Subjects had a significant decrease in body weight, waist circumference, body mass index (P < .01 in males, P < .05 in females), and body fat (P < .01 in males). The frequency of dietary habits such as eating snacks, eating out, and dining with others decreased, whereas the frequency of intake of foods such as whole grains, seaweed, fruit, and low-fat milk increased after intervention. After 16 weeks, program satisfaction was evaluated using a Web evaluation questionnaire, and most of the participants were highly satisfied with Web site components such as the loading speed, configuration, privacy, design, functionality, and contents.