In this study, antimicrobial activity of aminoreductone (AR), a product formed during the initial stage of the Maillard reaction, against methicillin-resistant Staphylococcus aureus (MRSA) was evaluated. The significant growth inhibition of all 51 MRSA isolates irrespective of drug susceptibility by AR was observed. The minimum inhibitory concentration (MIC) of AR ranged from 13 to 26 mM. The bactericidal activity of AR was evaluated by a killing assay with multiples of MIC, and it was recognized to depend on its dose. The combined effects of AR and antibiotics frequently used for the treatment of infections caused by Gram-positive and Gram-negative bacteria, such as amikacin (AN), ciprofloxacin, imipenem and levofloxacin, were examined. As a result, AR did not interfere with these antibiotic activities against 12 MRSA isolates selected and showed the advanced effect of growth inhibition in combination with antibiotics. Moreover, the inhibitory effects of AR were similar to those of AN, an antibiotic with known adverse effects, some serious. These findings show that AR is a naturally formed antimicrobial agent present in thermally processed foods with potential health benefits in medical practice.