Three hundred and sixty eight case histories of pulmonological patients and 127 case histories of other patients were examined retrospectively. Morphohistochemical investigation of the internal ear structure was performed on rabbits treated with different aminoglycoside antibiotics in various doses. Within 15 years (from 1978 to 1992) the incidence of adverse reactions to the antibiotic therapy in the pulmonological patients decreased from 33 to 5 per cent as a result first of all of the observation of the principles of antibiotic therapy by the physicians. Within 1992-1994 there were recorded no classical complications of the antibiotic therapy in the pulmonological patients. The only adverse reaction was the body temperature elevation. In 1994 there was stated the drug fever in 37 patients, 35 of them being treated without observation of the principles of rational antibiotic therapy. The aminoglycosides were used for the treatment of the main and concomitant diseases in 51 and 22 per cent of the patients respectively. Prophylactically the aminoglycosides were used in 12 per cent of the patients. In 15 per cent of the cases the use of the antibiotics was not indicated. The application of the routine methods for the control of the safe use of the aminoglycosides was stated to be unsatisfactory which made it impossible to detect nephrological complications. Nevertheless, changes for the worse were recorded twice as often as those for the better. The development of iatrogenic neuritis of the acoustic nerve to some extent associated with the incorrect regimens of the aminoglycoside therapy was stated in 3.9 per cent of the patients.