Dogs and wild canidae in Iran are highly infected with Toxocariasis This and the poor hygienic conditions ruling in rural regions let to expect the visceral larva migrans to be an entity of high incidence in this-country. Therefore, Patients Presenting with hepatomegaly, fever, leucocytosis and eosinophilia-specially when originating from villages-have to be surveyed for this syndrome. An effective therapy is not known. Monthly veterinary examination of domestic dogs and preventing small children to play with earth and materials which might be infected with dogs' feces-is the best way of prophylaxis.