Ankylosing spondylitis (AS) is a chronic inflammatory disease with a marked preponderance of affected males compared to females of approximately 6 to 1. During the last two decades, this circumstance stimulated several research groups to investigate serum levels of gonadal and adrenal sex hormones. From available results of cross-sectional studies, there seems to be no particular defect in secretion or production of adrenal, gonadal, and pituitary hormones. This is in striking contrast to diseases such as rheumatoid arthritis and other chronic inflammatory diseases. In the latter diseases, low serum levels of dehydroepiandrosterone (DHEA), DHEA sulphate (DHEAS), and testosterone have been described in an advanced chronic disease stage, whereas estrogen serum levels remain normal. Although AS is an inflammatory disease with signs of systemic inflammation such as elevated erythrocyte sedimentation rate or increased circulating proinflammatory cytokines, serum levels of adrenal and gonadal androgens are normal. It is unclear whether this can be considered as unexpected. It may be that inflammation does not reach the pituitary, adrenal, and gonadal glands or does not alter the aromatase complex in peripheral tissue. Furthermore, the inflammation-induced changes may be subtle so that only specific endocrine examination of these axes may reveal signs of alterations. In conclusion, current data on sex steroid hormones provide no straightforward explanation for the male predominance in AS. At the moment, there is no rationale to treat AS patients with sex steroid hormones.