Spontaneous reporting is an important tool in pharmacovigilance. Underreporting of adverse drug reactions (ADRs) is a common problem. In order to improve the ADR reporting, it is essential to improve the knowledge, attitude and practice (KAP) of the healthcare professionals. Various factors are related with the KAP of under reporting of ADR. Objectives: The present study was undertaken to evaluate the KAP regarding ADR reporting of among the prescribers of a tertiary care teaching hospital with ADR monitoring Liaquat University hospital, Hyderabad to get insight into the causes of underreporting of ADR. It was questionnaire based cross sectional study. A questionnaire (knowledge -1-10, attitude -11-23 and practice -24-28) was administered to 200 prescribers. The questionnaire was assessed regarding the ADR reporting. Microsoft excels worksheet and chi-square test was used for statistical analysis. A total 170(85%) prescribers completed and returned the questionnaire. Regarding definition of pharmacovigilance, specific aim of pharma covigiilance, functions of ADR monitoring center (AMC), 93%, 79% and 51.8% participants respectively could answer correctly. Only 54% respondents opined correctly that reporting of ADR is voluntary. 76.5% participants know the existence of AMC in the institution. 27.6% participants expressed that ADR reporting will generate extra work. 22.4% of participants reported ADR. Regarding reasons of under reporting many factors has been pointed out namely “do not know how to report”, “lack of knowledge about reporting procedure”, “not knowing where to report”, lack of time to report and lack of access to ADR form. The medical professionals are aware and have partial knowledge about ADRs. However, under reporting and lack of knowledge about reporting system are clearly evident. There is great need of creating awareness about ADR reporting system. Regular sensitization program to motivate the medical professionals may improve the ADR reporting.