Monitoring was conducted to investigate the occurrence of Grapholita dimorpha Komai in Korean apple orchards using sex pheromone traps. G. dimorpa showed four peaks per year: early May, from late June to early July, from late July to mid August, and from late August to September. After adult emergence of the over-wintered G. dimorpha, G. dimorpha catches was decreased significantly and increased again after July. In G. molesta traps, G. molesta and G. dimorpha were trapped by 98.8 and 1.2%, respectively. Conversely in G. dimorpha traps, G. dimorpha and G. molesta were trapped by 99.7 and 0.3%, respectively. The 30.6% of the moths from the damaged apple fruits were G. dimorpha. This is the first report on G. dimorpha in apple orchards in Korea.