BACKGROUND: Waist circumferences are widely used to diagnosis and assessment of obesity but various standards of the measuring waist circumference originate the confusion on diagnosis and assessment of obesity. According to this, this study is willing to light up standards of measuring waist circumference what is intimate with body mass index(BMI) and have a precision of intra observer and inter observers in repeated measurements of the waist. METHODS: Measuring of waist circumference by the 4 different standards(anterior superior iliac crest(ASIC), umbilicus, above 3 cm to ASIC, the thinnest area in the waist by the range of seeing) were performed on 102 people visiting Health Promotion Center of one medical collage hospital by two observers in each 2 times, total 16 times. Each data were analyzed by the relativity between the BMI and the each means of measuring waist circumference and by ANOVA test in intra observer and inter observer bias. RESULTS: The relation between BMI and data in measuring standard of ASIC of the waist circumference is the highest. (r=0.900) and the following umbilicus(r=0.896), above 3 cm to the anterior superior iliac crest(r=0.888), the thinnest area in the waist by the range of seeing(r=0.877), It is the lowest in intra observer bias that the thinnest area in the waist by the range of seeing, and ASIC in inter observer. CONCLUSION: It is desirable that ASIC is the standard of measuring waist circumference in the diagnosis of obesity and in measuring that by different two person, because of the highest relativity in BMI and the lowest inter observers bias. But the thinnest area in the waist by the range of seeing is desirable in measuring by same person because of intra observer bias.