Genetic analysis of antigene HLA-B27 was performed in 11 families with seronegative spondylarthritides (SSA). 107 family members were examined. In all of them determination of antigene HLA-B27 was done, and all the patients, as well as the family members who anamnestically had any rheumatic troubles, were checked completely. The analysis showed strong linkage between antigene HLA-B27 and the disease. Of 30 affected persons, 26 (87%) were HLA-B27 positive. The linkage has been mostly expressed in patients with ankylosing spondilitis (AS), (15 persons) i.e. all the affected by AS were HLA-B27 positive. Of 34 brothers, 19 (55.8%) were B27 positive, and of totally examined 35 children of the second generation, 15 (43%) were positive. Classical AS developed in 6 brothers (17.6%) and all were B27 positive. Disease distribution in relation to sex has been 4:1 for classical AS in favour of men. This proportion has been reducing if taking into account incomplete types of disease, as well as HLA-B27 negative patients, amounting to 1,5:1 HLA-B27 negative patients, as well as incomplete types of disease have been found exclusively in women. In our female patients the disease began later, with milder clinical picture, and minor X-ray changes.