Study the antagonistic test of fungus Chaetomium cupreum strain CH-1. Isolation of Chaetomium spp. from cassava leaves at Nikomsarngton-aeg, Muang Lopburi district, Lopburi province by Tissue transplantation method. The aim of this study to antagonistic test rice pathogenic fungi 4 types (Curvularia lunata strain TP, Curvularia lunata, Helminthosporium oryzae and Sarocladium oryzae). By test 2 method is dual culture and poison food technique (culture filtrate and crude extract of the fungus). The results showed that the antagonistic test of Ch. cupreum CH-1 by dual culture method can inhibit growth of Helminthosporium oryzae the best at 70.70%. The antagonistic test of culture filtrate Ch. cupreum CH-1 by poison food technique method showed that at 100% can inhibit growth of Helminthosporium oryzae the best is 27.90%. The antagonistic test of crude extract Ch. cupreum CH-1 with a solvent ethyl acetate, hexane and methanol by poison food technique method that crude extract from Ch. cupreum CH-1 well solvent ethyl acetate inhibit growth of Helminthosporium oryzae the best at 71.27%. The antagonistic test showed that of fungus Ch. cupreum CH-1 can inhibit growth the best of Helminthosporium oryzae.