Calcium homeostasis was determined from ionized calcium (Ca2+), total calcium (Cat) and bound calcium (Cab) levels, content of calcium-regulating hormones: calcitonin (CT) and parathyroid hormone (PTH). Lipid peroxidation (LPO) intensity was assessed from the blood plasma hydroperoxide level in 71 patients with bronchial asthma and chronic asthmatic bronchitis. The findings evidence that high blood serum levels of Ca2+ and Cab and a tendency to reduction of PTH content are characteristic of nonsevere and medium-severity atopic asthma. In bacterial asthma Ca2+ level increases at the expense of Cab, that is parallelled by elevation of CT content, as the disease progresses in severity. Blood CT level gradually decreases until it disappears completely in Stage III bacterial asthma, whereas PTH level grows. CT/PTH ratio may be an indicator of disturbed equilibrium in the CT-PTH hormonal system. In the course of treatment Ca2+ binding, most manifest in bacterial asthma, increases, CT level grows and PTH one reduces. A tendency to normalization of hormonal levels resultant from therapy does not eventuate in their complete recovery; hormonal levels remain shifted, this pointing to the essential contribution of endocrine mechanisms to calcium homeostasis disorders in asthma.