Biological properties of antigens of whole cells of C. burnetii in phase I (WCI), their residue (CMR) and extract (CME) obtained by extraction of C. burnetti with chloroform/methanol mixture were subjected to a comparative study. It was shown that CME is able to react specifically with sera containing antibodies against WCI. The inoculation of animals with CME, but not with WCI and CMR does not cause changes of humoral and cell immunity to Coxiella and does not strengthen nonspecific antibacterial activity, but it can stimulate the formation of antibodies. Morphological changes of internal organs of mice were most expressed after the CMR inoculation and were practically absent after the CME inoculation.