Abstract: The present investigation concerns with tne dermal reactions produced in various host species by the invading schistosomula in primary infection. Eight animal species including mouse, rat, hamster, jird, guinea pig, rabbit, rhesus monkey and pigeon were used. A small area of shaven abdominal skin exposed to 300 Schistosoma japonicum ceicariae was taken at different time intervals from each animal species. The dermal responses of various hosts to schistosomula varied with their suscepti-bility. In the case of pigeon, an unsusceptible host, the skin reaction was very severe. Cutaneous lesions were observed as early as 0.5-2 h post-infection and cellulat infiltration increased markedly with time. Thereafter the schistosomula were surrounded by many leucocytes with eosinophilic granules, and finally became disimegrated. In various mammalian hosts the skin reaction to the primary infection was slight, consisting of hyperemia, edema and cellular infiltration mainly by neutrophils with the exception of guinea pig in which the cellular infiltration was eosinophilic in nature (Figs. 1-9).