The objective was to study the prescribing pattern of Fixed Dose Combinations of a drug in patients with type 2 diabetes mellitus and also to assess the rationality of FDC of anti-diabetic drugs. FDCs are combination of two or more active ingredients in a fixed ratio of doses. Although FDCs have various advantages like improved compliance, reduction in dose and adverse effects, there are some disadvantages also. Therefore it must comply with some of the guidelines given by the WHO, to be counted as rational FDC. This study was carried out using 162 patients for a 6 months period among in-patients of general medicine department. Rationality of FDC was assessed using a 7 point criteria based on the WHO guidelines to analyse the rationality of FDC. Glimepiride and metformin was the most prescribed Antidiabetic FDC (32.71%) followed by sitagliptin and metformin (18.51%) and pioglitazone and metformin (13.58%). There were 10 different FDC of anti-diabetic drugs prescribed among them only 5 FDCs were found to be rational. The FDC of Glimepiride+Metformin scored highest of 11 and remaining 40% scored in the range 7-10 and 50% scored in the range 0-6 and 10% scored in the range 10-13. It was also identified that only 30% of the FDCs facilitated cost reduction when compared with the individual therapy