Acne is a chronic skin condition. At the time, share of patients (mostly female) with late acne (at the age of 25 and older) reaches 40—54%. In this age group, comedonal and papulopustular acne forms are presented. Aim: To study the skin microbiota condition in patients with late acne of mild to moderate severity during external monotherapy with 15% gel of azelaic acid (AA). Material and methods. We followed up 34 patients at the age of 25 and older, which were divided between three groups. The first control group included twelve female patients, in which skin microbiological features were studied with gas chromatography mass spectrometry. The second group (n=12) consisted of female patients with mild papulopustular late acne, who received 15% gel of AA as local monotherapy. The third group (n=10) consisted of female patients with moderate papulopustular late acne, who received 15% gel of AA as local monotherapy. Total treatment duration was four weeks. Results and conclusions. In acne tarda, in comparison with patients without acne, microbiota features were noted. There are significant differences regarding three microorganisms. Actinomyces viscosus, Clostridium difficile and Clostridium perfringens. It is uncharacteristic for acne vulgaris patients where Propionibacterium acnes dominate, which indicates more pronounced changes in microbiocenosis in late acne. Dynamics of microbiota indices (for Clostridium tetani, Lactobacillus spp. and Staphylococcus spp.) before and after local monotherapy with 15% gel of AA in correlation with positive trend of dermatologic index of symptoms scale indicate a high clinical effectiveness and positive effect on skin microbiota in female patient with mild to moderate papulopustular forms of late acne.