Provided is a pharmaceutical composition for reducing the risk in a patient at high risk for occurrence and/or recurrence of a cardiovascular event by administering the composition to the patient with a high ratio of oleic acid to stearic acid in plasma. The pharmaceutical composition contains ethyl icosapentate as its effective component. The composition is expected to reduce the risk in the patient at high risk for occurrence and/or recurrence of a cardiovascular event, and particularly to have a preventive effect on occurrence and/or recurrence of a cardiovascular event in the patient with a high ratio of oleic acid to stearic acid in plasma.