Esteya vermicola, as the first recorded endoparasitic fungus of pinewood nematode, exhibits high infection activity and shows potential as a biological control agent to combat the devastating pine wilt disease. However, there is still a paucity of data about this rare hyphomycete. In this article, two E. vermicola isolates, CBS 100821 and CBS 115803, were studied in the morphological characteristics and infection activities against pinewood nematode. Although both isolates parasitized the tested nematode, CBS 115803 showed significantly higher infection effectiveness than that of CBS 100821, to kill all the tested nematodes within 3 - 4 days. As to lunate conidia, a novel germination mode was observed and recorded.