A functional oil containing diacylglycerol (DAG) and monoacylglycerol (MAG) has been shown to have a strong anti-atherosclerotic effect in a mouse model. Among the lipid components, MAG is responsible for the beneficial effect with an enhanced antioxidant effect in the mouse model. In this report, several MAG-containing fatty acids (MAG-oleic acid [MAG-O], MAG-palmitic acid [MAG-P], and MAG-stearic acid [MAG-S]) were synthesized, and the antioxidant and anti-atherogenic activities were evaluated in vitro and in a cellular model. MAG-O had the strongest radical scavenging and antioxidant activities against copper-mediated low-density lipoprotein (LDL) oxidation and the strongest inhibitory activity against LDL-associated phospholipase A(2) and exhibited potent activation of paraoxonase activity, which contributes to the maintenance of antioxidant activity. All MAG species in this study exhibited inhibitory activity against glycation of apolipoproteins, in contrast to DAG. Oxidized LDL uptake into THP-1 cells was strongly inhibited by MAG-O treatment at a final concentration of 20 microM. MAG-O-treated cell culture medium showed the lowest production of malondialdehyde and lipid hydroperoxide compared to MAG-S and MAG-P. In conclusion, MAG-O had potent antioxidant, antidiabetic, and anti-atherogenic effects in vitro and in a cellular model.