this study was undertaken to compare the riboflavin status of rural women with different physical activity intensity and to determine factors influencing biochemical fiboflavin status. The study was carried out over three different farming seasons : planting (June), harvest(October) and interim(February) in two rural regions of Korea. One was a traditional farming region, the other a commercial farming region with heavier work intensity. Twenty women in the traditional region and eighteen women in the commercial region were involved. The intensity of physical activity was determined by a daily activity record. Body composition was assessed by bioelectrical impedence. Dietary riboflavin intake was measured by the food frequency method. Riboflavin biochemical status was assessed by erythrocyte glutathione reductase activity coefficient (EGR AC) and ruinary riboflavin excretion. The results from the EGR AC and urinary riboflavin excretion during the period showed the overall riboflavin status of the commercial farming women was significantly worse than that of the traditional farming women(EGR AC p<0.0001, urinary riboflavin excretion p<0.05). The traditional farming group had about 40% with risk of riboflavin deficiency, whereas the commercial farming group had about 70%. Overall mean nutrient intake was not significantly different between the two groups, however, overall mean percent lean body mass representing long term physical activity was significantly higher in the commercial farming group ( <0.005). It appears that the biochemical riboflavin status of traditional farming women was significantly influenced by riboflavin intake and crude nitrogen balance while the biochemical riboflavin status of the commercial farming women was significantly influenced by riboflavin intake and percent of lean body mass over the three seasons. (Korean J Community Nutrition 2(5) : 701∼710, 1997)