This report was undertaken to examine the correlationship between internal parasite infection and amount of milk production before and after vermicidal administration on F. hepatica and gastrointestinal nematoda infected cattle. The obtained results were as follows ; 1. Out of total number(358), the ratios of parasitic infected catle were 43.5%(156). Among them milking cattl. and Korean native cattle were 52.7% and 31.6%, respectively. 2. In this examination, 10 kinds of parasites were detected. Among them F. hepatica was encountered most frquently and also Buxtonella, Paramphistoma, Coccidim, Cestoda, and Trichur were encountered in order. 3. The average increased amount of milk production after vermicidal administration on F. hepatica and gastrointestinal nematoda infected cattle was 1.1Kg per day.