Background: Adverse drug reactions (ADRs) are global problems of major concern. Healthcare professional's knowledge and attitudes to ADR and ADR reporting play vital role to report any cases of ADR. Positive attitudes may favour ADR reporting practices by healthcare professionals. Objective: This study was aimed to investigate the KAP towards ADR reporting among HCPs working at primary outpatient care in Kuala Muda District Health Office, Kedah, Malaysia. Methodology: A cross sectional study was done by survey using a self-administered structured questionnaire. The questionnaire was distributed to all healthcare professionals working at primary outpatient care in Kuala Muda District Health Office, Kedah, Malaysia. Result and Discussion: The overall response rate was 87.4%. The mean knowledge score was 66.9% ± 19.86 for doctors and 76.9% ± 13.87 for pharmacists (p=0.03). 43.8% of the healthcare professionals did not aware of the blue card reporting system in Malaysia. Almost all of the respondents agreed that ADR reporting should be made mandatory and they recognized that it's their professional obligation to report any ADR. However, only 51.9% of doctors and 70.8 % of pharmacist had reported. Half of the respondents professed that ADR forms are too complex to fill and almost all of the respondents (90.4% doctors and 87.5% pharmacists) declared that they are lacking of time to fill in the report. 69.2% of doctors expressed that they have not been trained on ADR reporting which was contradicting with the pharmacists (12.5%) (p<0.001). Almost all respondents (82.7 % doctors and 95.8 pharmacists) concurred that ADR reporting should be taught in details to them. Conclusion: Respondents reflected inadequate knowledge on ADR reporting. The prevalence of unsatisfactory practices and attitudes among these HCPs contributed to failure to report ADR even if the ADR was identified. Educational intervention strategies can be introduced in order to promote ADR reporting.