The objective of the study is to evaluate the rational use of antibiotics among patients in a tertiary care teaching hospital. A prospective observational study was conducted, in which the antibiotic prescriptions in the medicine department were analysed. 128 case records of patients were identified and evaluated for the rational use of antibiotics for a period of 6 months. Overall 1269 drugs were prescribed in 128 prescriptions, out of which 287(22.62%) were antibiotics. Out of 128 prescriptions, there were 105(36.59%) Cephalosporins, 41(14.29%) Penicillins, 29(10.10%) Macrolides, 25(8.71%) Fluoroquinolones, 19(6.62%) Tetracyclines, 17(5.92%) Metronidazole, 11(3.83%) Aminoglycosides, 10(3.48%) Carbapenems, 7(2.45%) Lincosamides, 5(1.74%) Nitrofurantoin, 5(1.74%) Azoles, 4(1.39%) Sulphonamides, 3(1.05%) Rifamycins, 3(1.05%) Oxazolidones, 2(0.70%) Albendazole and 1(0.35%) Glycopeptides. 39(30.47%) prescriptions were prescribed with single antibiotic, 46(35.94%) and 25(19.53%) prescriptions were respectively prescribed with 2 and 3 antibiotics, 13(10.15%) prescriptions were prescribed with 4 antibiotics and 5(3.91%) prescriptions were prescribed with >4 antibiotics. 79(61.72%) prescriptions were rational and 49(38.28%) prescriptions were irrational. Out of 128 cases, 113(88.28%) were empirical, 9(7.03%) were prophylactic and 6(4.69%) were definite therapy. Prescriptions were analysed and rationality of prescriptions were assessed for parameters such as untreated condition, duplication of therapeutic group, inappropriate drug, contraindication, treatment without indication and inappropriate dose, duration and frequency of antibiotics respectively. Thus the study concludes that 61.72% of prescriptions were rational.