Background: Myocardial infarction (MI) is one of the most prevalent serious diseasesrnglobally, and its prevalence is increasing in Sub-Saharan Africa as risk factors for the diseasernrise. However, research on the magnitude and associated factors of MI in Sub-Saharan Africa,rnespecially Ethiopia, is limited. rnObjective: to assess the magnitude of myocardial infarction and associated factors amongrnacute coronary syndrome (ACS) patients attending at selected hospitals from January 2018 â€“rnFebruary 2021 G.C. rnMethods and materials: institution based retrospective study design was conducted. AllrnPatients with ACS was included in the study. Data was entered into Epi-info version (3.5.1)rnstatistical software package then was exported to SPSS software package version 24 forrnfurther analysis and p-value less than 0.05 was considered as statistically significant. rnResult: Among the total of 374 ACS patients, 338(90.4%) of them were MI. The patients'rnaverage age was 55.99 years old, +/- 12.98 years. Two hundred fifty nine (76.6%) of MIrnpatients were between the ages of 18 and 65, while the majority of patients, 82.5%, werernmale. Out of the total of 338 MI patients, 74.0% of them were ST elevation MI. diabetes wasrnprevalent risk factors in this study. Among the independent variables diabetes and systolic BPrnof patients (90-140 mmHg) and heart rate >100 b/min were significant association atrnmultivariate analysis. rnConclusion: MI was identified in the vast majority of ACS patients. Diabetic mellitus,rnsystolic BP (90-140 mmHg) and heart rate >100 b/min were significant association with MI.