Aim: The aim of the present study to determine the patterns of adverse drug reactions reported in the tertiary care hospital. Methods: This observational, retrospective study was done in the Department of Pharmacology, Darbhanga medical college, Bihar, India. A total of 200 ADRs were reported during the study period. Each ADR was analyzed for demographic data, relationship to drugs as per causality assessment, and frequency of ADRs. Results: A total of 200 ADRs were reported from both outpatients and inpatients of various departments. Most of the ADRs were found in females (55%) and patients of the age group 20 to 50 years (85%). Most of the ADRs were reported from the ART center (39%), dermatology (20%), oncology (11%), pediatrics (9%), and medicine (8%). The number of ADRs was distributed according to the department where they were reported. Overall, 40% of the ADRs are due to the anti-retroviral therapy, 29% due to the antibiotics, and 14% due to the nonsteroidal anti-inflammatory drugs (NSAIDs). Causality assessment was done by using the WHO-UMC scale, in which most of the ADRs were reported as probable (50%) followed by possible (48%). Severity assessment was done by a modified Hartwig and Siegel scale, in which most of them are mild (74%).The most commonly occurred ADRs were rash (40%), followed by nausea and vomiting (25%). Conclusion: The maximum number of ADRs were reported with ART drugs. So, it is advisable to have close monitoring of the ART to prevent ADRs in these patients. Serious ADRs such as SJS and TEN are most familiar with analgesics and sulpha antibiotics.