New adverse events and toxicities are identified as people live longer on ART and thernavailability of numerous new drugs and drug combinations make systematic monitoring of ADRrncritical in the HIV program. The contribution of health professionals to adverse drug reactionrndatabases is enormously significant, but under-reporting remains a major draw-back ofrnspontaneous reporting and the level of adverse drug reaction reporting in Ethiopia is alarminglyrnlow. Thus, a facility based cross sectional study was conducted in ART clinics of public healthrnfacilities of Addis Ababa city to assess the health care providersâ€™ knowledge, attitude & practicernon adverse drug reaction reporting.rnA total of 250 health care providers were included in the study by considering a 10% nonresponsernrate. Using proportional allocation to type of facilities; 9 facilities from Public hospitalsrnand 27 from health center based ART clinics were selected. Data was collected through a selfadministeredrnquestionnaire from health professionals selected by simple random samplingrnmethods. Observation was also used to verify existence of reporting forms in the facilities. Afterrnthe data collection was completed, data was entered and processed using EPI-info software andrnexported to SPSS for analysis.rnThe response rate was 93.22%. Among respondents (108)46.2% were aware of the existence of arnnational Pharmacovigilance center in Ethiopia and only 92(39.3%) of them knew where it isrnlocated. Among the respondents only 134(57.3 %) of them were aware of the yellow cardrnreporting scheme for reporting ADRs. Most respondents 208 (88.9%) agree the fact that ADRrnshould be reported spontaneously at a regular basis. 212(92.7%) of them also agree that reportingrnADR is part of their duty as health professionals & 197(84.2%) of the respondents believe thatrnreporting ADR should be mandatory. 101 (43. 2%) of the respondents encountered at least onernpatient on ADR in their clinical practice in the past one year and 96(41%) of the respondentsrnencountered at least one ADR on PLWHAs taking ART. But only 31(30.7%) of the respondentsrnreported that they noted the ADR they encountered on patient clinical or pharmacy record andrnonly 34(14.5%) of the respondents had ever reported ADRs.rnThe present study revealed the health care professionals have positive attitudes towards ADRrnmonitoring and reporting. But there are gaps in knowledge and practice of ADR reporting. Thernmajor reasons for under reporting are found to be concern that the report may be wrong, lack ofrnconfidence on diagnosis of ADR and unavailability of reporting forms.