The purpose of this study was to clarify the effect of vitamins K, D, and C supplementation on the development of osteopenia in calcium-deficient young female rats. Fourty nine female Sprague-Dawley rats, 6 weeks of age, were randomized into 7 groups with 7 rats in each group: Baseline control, 0.5% (normal) calcium diet, 0.1% (low) calcium diet, 0.1% calcium diet + vitamin K (30 mg / 100g food intake), 0.1% calcium diet + vitamin D (25 µg / 100 g food intake), 0.1% calcium diet + vitamin C (1.5 g / 100 g food intake) and 0.1% calcium diet + K, D and C. after 10 week of feeding, serum calcium, parathyroid hormone (PTH) levels and ALP activity were measured, and intestinal calcium absorption, renal calcium reabsorption, and bone growth parameters were evaluated. Calcium deficiency induced hypocalcemia, increased serum PTH level and ALP activity stimulated intestinal calcium absorption and renal calcium reabsorption and reduced maturation-related bone gain. Vitamin K supplementation in calcium-deficient rats stimulated elevation of serum PTH level, ALP activity delayed the reduction in femoral bone density and BMD. On the other hand, vitamin D supplementation in calcium –deficient rats stimulated intestinal calcium absorption via increased ALP activity with prevention of the abnormal elevation of serum PTH level, prevented hypocalcemia and retarded the reduction in femoral growth but had no effect on the femoral bone density and BMD. In contrast, vitamin C supplementation delayed the reduction in femoral bone volume, bone density, and BMD. However, no synthetic effect of vitamin K, D and C on intestinal calcium absorption, renal calcium reabsorption and bone mass was found.