The study was designed to compare the levels of the receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) in the serum and saliva of menopausal women and verify whether there is a correlation between concentrations of these cytokines and bone mineral density (BMD) of the femur and mandible. Blood and saliva samples were collected from a group of 60 women during menopause--30 untreated (control group) and 30 treated with hormone replacement therapy (HRT) (research group). Densitometry was conducted on the femoral bone and mandible. BMD in the research group was significantly higher than in the control group. The OPG concentration was slightly higher in the research group. The concentration of RANKL was slightly higher in the control group. Differences in RANKL/OPG between groups were not high enough to be statistically significant. Analysis of the RANKL in saliva revealed a significantly higher concentration of this factor in the control group. Observed beneficial effects of HRT on bone tissue may be exerted through the RANKL/OPG ratio, but further research is required to clearly confirm this thesis.