There are presented results of the clinical follow-up of 64 patients with moderate course of coxiellosis in whom the circulating immune complexes in the blood serum have been determined. All the patients received routine therapy, 29 patients were administered cycloferon intramuscularly, in dose of 2 ml, on the 1st, 2nd, 4th, 6th and 8th day of treatment. Clinical evidences of coxiellosis in the patients under routine treatment have been seen to be longer in the patients older than 50. Complex therapy with the use of cycloferon shortened the longevity of clinical evidences of the disease. By this the dependence of duration of clinical evidences of coxiellosis on the age disappeared. Content of circulating immune complexes of different sizes was higher in patients older than 50 years who received routine treatment only. Administration of cycloferon led to decreasing of activity of pathological immune complex processes and restoration of the normal content of common, average and low-molecular circulating immune complexes.