We studied the effects of daily intake of milk basic protein (MBP) on radial bone mineral density (BMD) in healthy adult women. Thirty-three healthy women were randomly assigned to a 6-month trial with either placebo or MBP (40 mg per day). The radial BMD of each volunteer was measured at the beginning of and at six months after the trial. The mean BMD value at the 6th month in the MBP group increased significantly at both 1/6 and 1/10 portion from the distal end of the radius, whereas that in the control group did not. The BMD gain of each volunteer in the MBP group was significantly higher than that in the placebo group. Thus a daily MBP supplementation of 40 mg in healthy adult women can significantly increase radial BMD.