Maximizing peak bone mass is advocated as a way to prevent osteoporosis. To evaluate the peak bone mass and the affecting factors in Korean women, we analyzed bone stiffness in 116 middle school students, 118 high school students and 115 female college students by using the Achilles densitometer (Lunar Corporation). Peak bone stiffness of Korean women was relatively lower than that of white women (94% of white women) and a rapid rise of bone stiffness was observed in those subjects 3-4 years after menarche. In adolescent females without menstruation, the bone stiffness was lower than that of adolescent girls with menstruation. The factors affecting the peak bone mass was similar to the risk factors of post menopausal osteoporosis: menstruation status, calcium intake and physical activity. The amount of calcium intake in Korean girls at the critical age (3-4 years after menarche) was lower than the RDA (requirement of daily allowance) at this age. To improve any program aimed at maximizing peak bone mass, further intensive study will be required to evaluate some other common factors affecting peak bone mass in Korean.