We examined effect of milk and dairy products on the bone mineral density (BMD) and alkaline phosphatase (ALP) activity of ovariectomized rats. Female rats were ovariectomized (OVX), and other rats received a sham operation. The OVX rats were assigned to 4 dietary groups: the control (OVX-Cont.) group, skimmed milk (OVX-Milk) group, fermented milk (OVX-Yogurt) group, and whey (OVX-Whey) group. Eighty-four days after feeding the experimental diets, the BMD level of the femur was significantly higher in the OVX-Milk and OVX-Whey groups than in the OVX-Cont. group. The level of serum ALP activity was significantly lower in the OVX-Cont. group than in the OVX-Milk and OVX-Yogurt groups. These results imply that milk or dairy products improved the BMD level, and had an effect on the ALP activity of OVX rats.