Introduction. Osteoporosis is a disease characterized by decreased bone density and destruction of the microarchitectonics of the bone structure. This leads to increased bone fragility and risk of fracture, particularly of the hip, spine, wrist and shoulder. Osteoporosis is known as „The Silent Epidemic of the Century“ because bone loss occurs without symptoms. An altered ovarian function is one of the most common causes of osteoporosis. Indicators for altered bone homeostasis are the changes in serum levels of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). Objective. The aim of current study was to determine the activity of alkaline phosphatase (ALP) and serum concentrations of MMP-9, MMP-13 and TIMP-1 in the ovariectomized rats. Materials and Methods. An experiment was performed on 35 female Wistar rats at reproductive age – 2 months divided into 2 groups: group 1 (G1)-20 animals were sham-operated (sham) and group 2 (G2)-15 were ovariectomized (ovx). Results. The concentrations of ALP, MMP-9, MMP-13 and TIMP-1 in G2 were significantly increased compared to G1 (p<0.05). Conclusion. Our study confirmed that the serum activity of ALP, which is a marker of bone formation, was elevated in rats with OVX-induced osteoporosis. Although the level of TIMP-1 is increased, the level of MMP 9 in G2 is also increased, that confirms the thesis that MMP-9 may be a marker for osteoclast activity.