PURPOSE: Innovations in information technology offer new opportunities for creative application of personalized, tailored feedback strategies for improving dietary adherence. We developed and tested a real-time diet-monitoring and feedback system using hand-held computers. The goals were to increase diet self-monitoring, reduce the burden of monitoring food intake, and increase adherence to dietary goals within a clinical trial. METHODS: Participants were 33 women in the Diet Modification arm of the Women's Health Initiative (WHI). After using focus groups to determine system features, women used the Personal Digital Assistant (PDA)-based system for 1 month and received immediate and weekly tailored feedback. The process and outcomes were evaluated using real-time food records collected through the PDAs; surveys; and self-reported food frequency questionnaires. RESULTS: Participants significantly increased self-monitoring, improved their attitudes toward self-monitoring, and met their dietary goals more often. Reported total fat intake and percent energy from fat decreased significantly. There was a modest decrease in mean caloric intake. DISCUSSION: The pilot study findings support the largely untapped potential of hand-held computers for improving diet monitoring and diet adherence, particularly within a clinical trial.