Elevated serum cholesterol is a risk factor in the development of coronary artery disease. Magnesium has been reported to decrease total serum cholesterol, low density lipoprotein, and very low density lipoprotein, and increase high density lipoprotein. A randomized, double-blind, placebo-controlled, crossover study was completed to determine if supplemented magnesium, in the form of magnesium oxide, would produce changes in the lipid profile. Fifty normal volunteers received placebo or magnesium oxide, 400 mg capsules, twice a day for 60 days, then switched to the alternate treatment. Weight, height, blood pressure, serum potassium, serum magnesium, and a lipid profile were determined initially and after each treatment. Analysis of variance (ANOVA), comparing the mean of each component of the lipid profile at baseline and after each treatment, showed no significant difference. In conclusion, supplemental magnesium oxide did not produce statistically significant changes in the lipid profile in this group of healthy volunteers.