The effect of zinc and vitamin K₂ (menaquinone-7) on bone components in the femoral tissue of female elderly rats was investigated. Rats were orally administrated either vehicle (distilled water), zinc sulfate (1.0 mg Zn/100 g body weight), menaquinone-7 (MK-7, 0.5 mg/100 g) or zinc (1.0 mg/100 g) plus MK-7 (0.5 mg/100 g) once a day for 7 days. Femoral dry weight was significantly increased by the administration of both zinc and MK-7, although a significant change was not seen by zinc or MK-7 alone. Calcium content in the femoral-diaphyseal and metaphyseal tissues was significantly increased by zinc administration. Such an increase was not found by MK-7. Bone calcium content was synergistically enhanced by the administration of both zinc and MK-7. Alkaline phosphatase activity and deoxyribonucleic acid (DNA) content in the diaphyseal and metaphyseal tissues were significantly increased by zinc or MK-7 administration; these increases were additively enhanced by both zinc and MK-7. Moreover, the intake of supplement containing both zinc (1.675 mg/100 g) and MK-7 (168.8 μg/100 g) once a day for 15 days caused a significant increase in femoral dry weight, alkaline phosphatase activity, DNA, calcium and zinc contents in the diaphyseal and metaphyseal tissues. This study demonstrates that the administration of both zinc and MK-7 can enhance additively or synergistically bone components in female elderly rats, suggesting a role in the prevention of osteoporosis with increasing age.