Background: Febuxostat has been reported to have a stronger effect on hyperuricemia than allopurinol. Methods and Results: Cardiac surgery patients with hyperuricemia (n=141) were randomized to a febuxostat group or an allopurinol group. The study was single-blind, so the treatment was not known by the investigators. The primary endpoint was serum uric acid (UA) level. Secondary endpoints included serum creatinine, urinary albumin, cystatin-C, oxidized low-density lipoprotein (LDL), eicosapentaenoic acid/arachidonic acid ratio, total cholesterol, triglycerides, LDL, high-density lipoprotein, high-sensitivity C-reactive protein, blood pressure, heart rate, pulse wave velocity (PWV), ejection fraction, left ventricular mass index (LVMI), and adverse reactions. UA level was significantly lower in the febuxostat group than the allopurinol group from 1 month of treatment onward. Serum creatinine, urinary albumin, cystatin-C and oxidized LDL were also significantly lower in the febuxostat group. There were no significant changes in systolic blood pressure, PWV, and LVMI in the allopurinol group, but these parameters all had a significant decrease in the febuxostat group. Conclusions: Febuxostat was effective for high-risk cardiac surgery patients with hyperuricemia because it reduced UA more markedly than allopurinol. Febuxostat also had a renoprotective effect, inhibited oxidative stress, showed anti-atherogenic activity, reduced blood pressure, and decreased PWV and LVMI.  (Circ J 2013; 77: 2043–2049)