In this paper, a high efficiency asymmetrical half- bridge converter (AHBC) with an improved coupled inductor rectifier (CIR) is proposed. The proposed converter can eliminate a DC-offset current in a transformer using a coupled inductor at rectifier stage. In the rectifier stage, the proposed converter has small diode conduction loss because there exists only one diode in the rectifier current path. In addition, primary switches have wide zero voltage switching (ZVS) range, which improves light load efficiency. Experiments were conducted with a 200 W prototype of 250-400 V input and 48 V output conditions.