This study was performed to investigate the effect of breakfast regularity on eating habits, nutritional and health status in adult men and women. Also, eating habites and nutritional status expressed as percentage of recommended energy intake in IB(Irregular Breakfast group) were studied. Proportions of IB in men and women was 23.7% and 31.1%, respectively. In men, IB had irregular mealtime, overeating tendency. Also, they consumed high-fat meat and alcohol more frequently than RB (Regular Breakfast group). Total energy intake showed no significant difference between which two groups. Energy intakes from dinner and alcohol were higher in IB than in RB. Nutrient and food intakes were lower in IB than in RB. Percent body fat of IB was higher than that of RB. Weight, triglyceride and prevalence of fatty liver were higher in IB than in RB. In women, IB had irregular mealtime, and overeating tendency. Also, they had more frequent eating out and alcohol consumption. Total energy intake was lower in IB than in RB. In men, nutrient and food intakes were lower in IB than in RB. But health status showed no significant differences between two groups. In men, energy intakes from alchol and dinner were higher in +RDA group(percentage to recommended energy > 125%) than in other groups of IB. But energy intake from carbohydrate was lower in +RDA group. -RDA group (percentage to recommended energy < 75%) had Ca and vitamin A intake less than RDA. In women, +RDA group had overeating tendency. Also, they had more frequent eating out, high-fat meat, and alcohol consumption than other groups of IB. Energy intakes from dinner, snack and fat were higher in +RDA group. But -RDA group had protein and vitamin A intake less than RDA. From our study, it seemed that breakfast irregularity led to undesirable eating habits and had relation with increase of percent body fat. Breakfast regularity seemed to be very important to maintain a nutritional balance.