Introduction: One of the most common metabolic bone disease is postmenopausal osteoporosis. There is data that pineal melatonin (MLT) is decreased with age and that menopause is correlate with a substantial decrease in melatonin secretion and increased rate of pineal gland calcification. Because of this, in the present study, the authors aimed to assess pinealectomy-induced melatonin deficiency in menopause which may be a contributing factor in the development of postmenopausal osteoporosis. Materials and Methods: A total of 49 young Wistar-Albino rats were included in the study. Some groups underwent bilateral ovariectomy (OVX) via the dorsal route, and pinealectomy (PX) was performed with Kuszack and Rodin method. Following PX and OVX, selected groups were given a dose of 5 mg/kg/day injected intraperitoneally. The authors evaluated bone mineral density (BMD) of the femur by dual-energy X-ray absorptiometry. The BMD of femur named as proximal 1/3 (RI), middle 1/3 (R2), distal 1/3 (R3), and total (R4). Results: Compared with the sham group, PX I MLT group had significantly higher BMD values at R3 subregion. There is no statistically significant relationship between PX+OVX group and PX+OVX+MLT group at subregions. Compared with the OVX + MLT group, PX+OVX+MLT group had significantly higher BMD values at R1, R3, and R4 subregions. Conclusion: PX significantly increases BMD at R3 subregion, but its not reversed by exogenous MLT administration. OVX cancelled the effects of PX with respect to increases in the levels of reached bone mass. Exogenous MLT administration to OVX and PX group did not increase BMD values.