Osteoporosis has been found as a complication observed in ankylosing spondylitis (AS) patients more frequently as compared to healthy population. The aim of the study was the estimation of bone tissue metabolism in male population suffering from AS after having taken into account such factors as a high risk of incidence of osteoporosis and potential danger of permanent immobility. The research comprised in 58 patients with AS (age: 50,1±13,1; duration of illness 17,1±11 years) and 60 healthy men chosen at random. The study of bone density was carried out in the distal part of radius by means of the dual energy X-ray absorptiometry (DXA) method. The group of AS patients was divided into 2 groups depending on the T score. The first subgroup consisted of 19 men with T score >–1.0 (age: 43±12; T score -0.5±0.4), and in the second subgroup there were 39 men with T score Ł–1.0 (age: 54±12; T score –2.0±0.8). All patients underwent clinical research. The erythrocyte sedimentation rate (ESR), was also measured according to Westergreen method. Radial immunodiffusion was incorporated to estimate the value of reactive proteins (CRP and ACT). Furthermore, ELISA method was used to estimate the concentration of the interleukin 6 (IL-6) and the concentration of biochemical markers of osteoporosis (AP-B, DpD). Based on the obtained data we conclude that: a higher disease activity, assessed by the concentration of reactive proteins markers as well as by analyzed proinflammatory cytokines, causes an increase in the loss of bone tissue. Finally, an increase of disease activity estimated by the reactive proteins markers and inflammatory cytokines stimulates bone resorption with the limited influence on the process of bone formation.