Aim: to evaluate the pattern of adverse drug reaction in geriatric inpatients of medicine in a tertiary care center. Methods: This prospective observational study was carried out in the Department of Pharmacology, A.N.M. Medical College and Hospital, Gaya, Bihar, India for 15 months. Patients more than 60 years of age of both sex, patients those who give consent to participate in the study. A causality analysis was done as per the WHOUMC and Naranjo probability score, preventability of an ADR was assessed by modified schumock thornton scale, severity was evaluated by modified Hartwig and siegel scale, which gives an overview of the severity of ADR whether it is mild, moderate or severe in nature. Results: Total of 50 patients had the ADRs in the 7 medicine units in the study period of 12 months. Majority of the patients showed the ADRs were in the agegroup of 60-65 years n=20 (40%) while least 5 (10%) in 80-85 years age group. Out of total 50 ADRs, Male were 27(54%) and femaleswere 23 (46%). Most of the ADRs were of type A 25 (50%) followed by type C - 20 (40%). In majority of the instances, it was antimicrobial agents 16 (32%) in which metronidazole was the most common 6 (12%), next was amoxicillin and clavulanic acid combination 5 (10%) followed by antimicrobial agents,NSAIDs 11(22%) were common- in which aspirin 5 (10%) was common. Next was ACE inhibitors were alsoinvolved 5 (10%), anti-diabetic 4 (8%) anddiuretics 3(6%). Another class of drugs that showed adverse drug reaction were anticoagulants 3 (6%) bronchodilators 2 (4%), hypolipidemic drugs 2 (4%) and calcium channel blockers 1 (2%). According to WHO, only 02 (4%)ADRs were certain while 38(76%) were possible. According to Naranjo’s only 3 (6%) ADRs were possible while 47 (94%) were probable. The analysis of the severity of ADRs was done according to modified Hartwig Seigle’s scale, majority of ADRs 23(46%) were mild, 16 (32%) moderate in nature and 11 (22%)ADRs were severe in nature. Conclusions: Age is not an independent risk factor of ADRs and suitable monitoring and regular medication review can reduce the incidence of ADRs in geriatric people.