An adverse drug reaction (ADR) is an injury caused by taking a medication. ADR’s may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs. The aim of the present study was to monitor, assess and report the suspected adverse drug reaction at a tertiary care hospital. Prospective observational study was conducted for a period of six months and hospitalized patients were recruited in various wards based on inclusion and exclusion criteria. Each adverse drug reactions were assessed for its causality and severity based on “Naranjo’s causality assessment scale” and “Modified Hartwig and Siegel scale”. “Schumock and Thornton scale” was applied to assess preventability of adverse drug reactions. A total of 137 ADR’s were identified from 112 patients during the study period. Patient demographic data revealed that 36% of ADRs were reported from the age group of 31- 45 years, 52% of ADR’s were documented from General Medicine ward, 25% from surgical ward, and 16 % from paediatric. ADR monitoring need to be done in hospital setting continuously so that untoward effect caused by different medicines can be identified and documented. Strategies such as arranging educational programme for health care professionals related to importance of ADR’s reporting would substantially reduce ADR’s occurrence in hospital ward and remaining from other wards.