This study estimated the isoflavone intake level in Koreans using Food Frequency Questionnaire and analyzed related variables. The results showed that the average daily intake of isoflavone in adults was shown as 23.1 mg. The isoflavone intake level at 50 percentile was 16.9 mg (0~190 mg), and 10% of adults took almost 50 mg of isoflavone a day and 10% took about 5 mg a day. The major food sources for isoflavone in Koreans were in the order of soybean, soybean paste, soy milk, soybean curd (tofu), and bean sprouts; the intake was different depending on age, educational background, occupation, economic standard, and family type. The result showed higher isoflavone intake levels in the group over 30 years old and the highest isoflavone intake in subjects working in farming/fishery, followed by housemakers. According to the differences by families the families with elderly members showed 50% higher isoflavone intake than young families with friends or siblings. Depending on related ecological variables, therefore, various nutrition education programs should be developed for a variety of intakes of soybean foods, along with easy and simple cooking methods as parts of continuous research.