In this paper, a bridgeless Cuk derived AC/DC converter is proposed. The present circuit topology separates the input PFC current and output voltage-regulation current, which reduces the switch current stresses and improves system thermal management compared to the conventional bridge and bridgeless Cuk topologies. In addition, the proposed bridgeless topology has semi-soft switching function of all active switches to reduce converter switching losses. Therefore, the switch conduction losses and switching power losses all can be decreased due to the reduced current stress and semi-soft switching function. To understand the proposed Cuk derived converter, the circuit operation is explained and the steady-state behavior is analyzed. Finally a prototype system with DSP TMS320F28335 controller is implemented. Some simulation and experimental results are offered to verify the validity of the proposed bridgeless Cuk derived PFC converter.