This case control cross sectional study was carried out in the Department of Biochemistry, Mymensingh Medical College in collaboration with Cardiology Department of Mymensingh Medical College Hospital, Mymensingh during the period of July 2004 to June 2005. The aim of the study was to explore the status of serum magnesium among acute myocardial infarction (AMI) patients as a means to monitor the possibility of management of these patients. A total of 100 subjects were selected and were grouped as Group I (50 healthy control subjects) and Group II (50 subjects of AMI Cases). Serum magnesium was estimated by colorimetric method from each sample. Statistical analysis was done by using SPSS windows package. Among the groups, mean±SD (Standard Deviation) of Group I and Group II serum magnesium were 2.16±0.25 and 1.71±0.17mg/dl respectively. By comparing Group I with Group II highly significant difference were found in case of serum magnesium (p<0.001). It is evident from the study that serum magnesium level significantly decreases among acute myocardial infarction patients in Bangladesh.