Background: Adverse drug reactions (ADRs) are among the top leading causes of death, adversely affect the quality of life by increasing hospital stay, treatment cost, and morbidity. Spontaneous reporting of ADRs by health-care professionals (HCP) helps in signal detection and enables regulatory agencies to formulate drug use guidelines, issue warnings, or even ban/withdraw the drug from the market. Dissemination of knowledge regarding the patterns of ADRs seen in adverse drug reaction monitoring centers (AMCs) among HCP will enable to promote awareness on ADRs, help in early detection, and encourage them to be more vigilant so as to prevent recurrence of ADRs. Aims and Objectives: We conducted an observational study, with the following objectives. The aim of the study was to determine the pattern of ADRs reported to AMC at PESIMSR, causality assessment, severity score, and preventability. Materials and Methods: We conducted an observational, retrospective, and questionnaire-based study in PESIMSR AMC, Department of Pharmacology. The study period was between January 2016 and December 2016. All ADRs reported to the AMC in the above period were collected by convenient sampling method. Data collected includes patient characteristics such as age, gender, details of the reaction, details regarding suspected drugs, treatment, and outcome of ADR details as outlined in the standard CDSCO ADR notification form. Data were entered in SPSS version 22. Descriptive statistics used and values are expressed in frequency and percentages. Results: A total of 153 cases were taken for analysis. Among them, 52% were males and 48% were females. The incidence of ADRs was higher (26%) among third and fourth decade than other age groups. Most frequent classes of drugs causing ADRs are antibiotics (44%) followed by analgesics (10%) and oral hypoglycemics (6%). The most frequently reported ADRs were cutaneous reactions. According to the WHO scale for causality assessment, 59% were possible ADRs. According to modified Hartwig Seigel’s severity assessment scale, about 16% were assessed as severe reactions. About 39% were probably preventable ADRs as assessed by modified Schummock and Thornton scale. Conclusion: Hospital-based ADR monitoring and reporting programs aim to identify and quantify the risks associated with the use of drugs. This study gives an insight to emphasize the awareness to the health-care providers on vigilant monitoring of ADRs and promptly reporting the same so as to prevent the occurrence of the reactions in vulnerable population.