The significance of the species and individual level in determining the hosts as a category of helminth life cycles is pointed out. From the viewpoint of species level, the categories of intermediate host and definitive host are ascribed to certain organisms as representatives of a certain species on the basis of the fact that a respective stage of helminth life cycle can take place inside them. From the viewpoint of individual level, these types of hosts are determined on the basis of associations between the helminth individual and host individual. In order to avoid discrepancies, which might occur in determining the host type in these ways, it is proposed that the organism, which was determined as intermediate or definitive host at the species level, should be regarded identically also at the individual level. In addition, the existence of retarding definitive host (s.l.) is substantiated on the example of helminths which survived the interorgan migrations and passed to the offsprings through the intrauterine or transmammary route.