Investigators planed to conduct a randomized, controlled, crossover trial to examine the effects of daily walnuts intake among Korean subjects with metabolic syndrome. Primary objective of this study was to investigate the effects of daily walnut intake on changes of metabolic syndrome indices in Koreans with metabolic syndrome age over 30 years old. This study was consisted of four periods: run-in, first intervention, wash-out, and second intervention phases. As 16 weeks of first intervention period began after the run-in phase, the subjects were randomly assigned into one of two groups: walnut group and control group. Participants in walnut group consumed 45 grams of walnuts on a daily basis and participants in control group were provided iso-caloric white bread for first 16 weeks. After the first intervention and wash-out period (6 weeks), second intervention which is crossover of first intervention was started during the next 16 weeks. Anthropometric measurements and biochemical analyses were done at the beginning and the end of each intervention (0, 16, 22, and 38 weeks of trial). Habitual diet was randomly observed using 3-day diet record once during each phase.