1. To evaluate the distribution patterns of subcutaneous fat and muscle 679 male and 950 female Japanese volunteers were investigated by means of ultrasonic tomography.
2. With an increase in age the thickness of the anterior thigh muscle decreased, whilst subscapula muscle thickness was independent of age.
3. In comparing a resident in a city (Tokyo) to a country resident (farmer in Yamagata) the arm muscle of a farmer was thicker than that of a cityman, while the thigh muscle was lower in the farmer.
4. Muscle thickness is related to its cross-sectional area and the muscle area is affected by activity level in daily physical exercise.
5. The present data indicate that the farmer makes less use of his legs than does the city dweller.
6. There were significant correlation coefficients between fat thickness and HDL-C, i.e. the highest correlation was observed at the abdomen, suggesting that the fat thickness of the abdomen is one of the important factors for evaluating serum cholesterol level.