Background: An Adverse drug reaction (ADR) is an injury caused by taking medication. ADRs are major threat to patient therapy as it results in significant morbidity, mortality and health care costs. Objective: To monitor and evaluate the ADRs in a tertiary care hospital. Methods: This observational and cross-sectional study was conducted for 10 months from January 2019 to October 2019 in an inpatient setting of a tertiary care hospital in Mangalore using ADR reporting form. Patients of all age groups, either sex and only inpatients were included. Results: ADR’s caused by Intravenous route were the highest occurring comprising of 60.46% followed by 29.53% causing by oral route of administration. Among the organ systems skin membrane were mostly affected which is of 60.46% and 13.95% of ADR’s were present as CNS and neurological disorders. Drug categories suspected to cause ADRs were related to antibiotics (39.53%), G1 drugs (16.27%), and the remaining classes of drugs like anti-diabetics, anti-coagulants etc.11 (26%) ADR’s were found to be mild, 25 (58%) were moderate and 7 (16%) of ADR’s were found to be severe according to severity assessment. Conclusion: Adverse drug reaction is a significant limitation to the success of therapeutics and to deal with this problem pharmacovigilance program is initiated to emphasise the importance of monitoring and reporting of ADRs to ensure the safety use of drugs. However the quality and quantity of the ADR reports can be improvised only through educational programs that guide the healthcare providers in recognising and reporting the ADRs efficiently.