The effect of exercise on serum cholesterol and triglyceride concentration and on urinary creatinine and 3-methylhistidine excretion was studied in eight healthy women, aged 21 to 25yr. Subjects were tested before and after a 3-day experimental period, during which 1000 times rope-jumping a day were performed. Serum cholesterol and triglyceride levels decreased significantly after exercise. Urinary excretion of creatinine and 3-methylhistidine slightly increased after exorcise.