Research objective is to study the stability and shelf life of Biomayrin capsules, which were obtained bychemical modification of high-molecular weight compounds by incorporation into polymers.Materials and Method: “Biomayrin” capsules weighing 600±6 mg containing isoniazid, rifampicin,ethambutol, polygalacturonic acid and calcium stearate, obtained by disk dosing into capsules No.0. Theshelf life was set by the method of “accelerated aging” when the samples were stored in PVCA1 blisterpacks (20 capsules each) at the temperature of 600? in the thermostat TV-80-1. The tests “Decomposability”of capsules and “Average mass and homogeneity by mass” were conducted in accordance with therequirements of the State Pharmacopoeia of the XIV edition. Experiments were conducted in at least threerepetitions. Decompressibility of capsules was determined on PJ-3 Tablet Four-usage Tester (China).Isoniazid, rifampicin and ethambutol were quantitatively determined in solution by spectrophotometry (SF).The analysis was performed on SHIMADZU UV-1601, UV-VISIBLE spectrophotometer in 1 cm cuvetteagainst the background of the solvent. The pH value was controlled with the EV-74 universal ionometer.Mathematical processing of the results was carried out according to General monograph. 1.1.0013.15“Statistical processing of chemical experiment results” using standard computer programs MsExcel.Results: The results on properties of capsules at storage of 600? and 250? are shown, after dissolution thecontent of active substances (isoniazid, rifampicin and ethambutol) in preparations was within the limitsof regulated norms (60-120 mg), at 600? it is for isoniazid 101, 7-106.7 mg, at 250? 100.1-106.0 mg forrifampicin the regulated norm was 72-132 mg and at 600? it was 94.2-92.2 mg, and at 250? it was 94.7-91.2mg, as well as ethambutol hydrochloride content was 60-120 mg and at 600? it was 62.5-60.5 mg, and at250? it was 62.0-60.2 mg.Conclusion: “Biomainrin” capsules with different expiration dates were investigated, and also the changeof their quality according to the indicators “Active substance content” and “Dissolution” was found. It wasshown that after the expiration of the shelf life there is a gradual decrease in the active ingredient content