AIM: Adverse drug reaction is noxious and unwanted reaction to drugs at dose used in humans for diagnosis, treatment or prophylaxis. Adverse drug reaction monitoring is an area of drug information that has been given little attention yet. Spontaneous reporting is currently the major back bone for the detection of adverse drug reactions. The objective of this study was to assess the knowledge, attitude and practices of adverse drug reaction reporting among health professionals in selected health facilities in southwest Ethiopia. METHOD: A cross-sectional study design was used among health professionals in selected health facilities in January 2010. Prescribers other than physicians, junior pharmacy technicians and also health assistants were excluded. Data was collected using self administered questionnaires from volunteered physicians (Medical interns and above), nurses (Diploma and above) and Pharmacy professionals (Diploma and above) and analyzed using SPSS version 16.0. RESULTS: A total of 82 health professionals were participated in the study. From those 82 participants, only 19 (23.17%) and 21 (25.61%) knew the existence of national reporting system and a yellow card of adverse drug reaction reporting form. Thirteen (15.85%) participants encountered adverse drug reaction in the past 12 months in their clinical activities, but none of them reported to responsible body. Even though the participants’ knowledge and practice were inadequate, most of the respondents 47 (57.31%) agreed that adverse drug reaction reporting is part of duty of them and important to the public in general and to the patient in particular. CONCLUSION: There was no documentation and reporting of adverse drug reaction, which might partly be explained by lack of knowledge and misconceptions about spontaneous reporting. Our study strongly suggests that there is a great need to create awareness and to promote the reporting of adverse drug reaction amongst health professionals, which will lay a solid foundation for healthcare professionals to be diligently involved in quality pharmacovigilance and spontaneous reporting in their future practices.