This paper proposes a high-efficiency three-level (TL) dc-dc converter with reduced circulating current and rectifier voltage stress by using coupled inductor in the rectifier circuit. Because of decreased circulating current, the conduction loss in the primary circuit is reduced. In addition, since the rectifier diodes with low forward voltage drop can be employed due to the small voltage stress, the conduction loss of rectifier diodes can be reduced. Therefore, the efficiency can be increased due to the reduction of the conduction losses in the primary circuit and rectifier diodes. The characteristics of the proposed converter are analyzed and compared with other TL converters. The validity of the proposed converter is verified by the experimental results of the prototype with 540-600 VDC input and 750 W (48 V/15.625 A) output.