OBJECTIVES:  Investigate correlation between the number of manufacturing companies and the percentage of cost variation of antidiabetic drugs in Ukraine. METHODS:  1) retrospective analysis of 1792 inpatient’s medical histories with T2DM; 2) frequency analysis of the used treatment regimens; 3) ATC/DDD-methodology. RESULTS:  The retrospective analysis showed that monotherapy was used in 25 % of cases. Of these, 16 were treated by metformin, 5 % – glimepiride, 4% – gliclazide. So, metformin, glimepiride and gliclazide have been selected for the research. Pharmaceutical assortment of peroral antidiabetic drugs, manufacturers, minimum and maximum costs of generics in pharmaceutical market of Ukraine have been established in price list of the largest national distributor. According to the ATC/DDD-methodology DDD of metformin is 2000 mg, gliclazide – 60 mg, glimepiride – 2 mg. The investigated period was 2011-2014. As a result of ATC/DDD-analysis it has been found that the cost of DDD of monotherapy with metformin ranges from 1,28 to 1,55 UAH (in minimum costs of generics) and 3,05-5,46 UAH (in maximum costs of generics), with glimepiride – 0,66-1,06 and 1,88-3,42, respectively, with gliclazide – 0,31-1,26 and 1,62-3,97 UAH, respectively. The number of manufacturing companies of metformin was 7-9, glimepiride – 8-9, gliclazide – 3-5. Spearman rank correlation of the investigated treatment regimens indicates the weak negative association between the number of manufacturing companies and the percentage of cost variation (p>0.05). CONCLUSIONS: Our results showed a weak negative association between the number of manufacturing companies and the percentage of cost variation of peroral hypoglycemic drugs that were selected for the investigation. Probably, it is associated with small number of manufacturers of antidiabetic drugs in the pharmaceutical market of Ukraine and, maybe, distortion of lows of the market and competition in condition of political and economic instability of the country.