We collected 220 ticks from 58 dogs infected with Hepatozoon canis from 1990 to 1992 in Yamaguchi and Fukuoka prefectures, the western provinces of Japan. These ticks were identified as Haemaphysalis campanulata, H. longicornis, H. flava, Ixodes ovata, and I. nipponensis. By histopathological examination of these ticks, two oocysts which seemed to be those of H. canis were observed in the haemocoele of an adult female H. longicornis and a nymph H. flava tick. The oocyst, about 300×150 μm in size, was composed of 50 to 70 sporocysts with 10 to 16 banana-shaped sporozoites each.