Two tapeworms, Taenia saginata and Echinococcus granulosus, cause serious economic and human health problems in several parts of the world. Some of these Problems might be solved if a cheap, easy and safe vaccination could be developed. Before a vaccination against adult tapeworms can be developed it is necessary to know how intestinal tapeworm populations are controlled by immune mechanisms. For this purpose laboratory modeis have been used involving mainly species of Hymenolepis in rodents and especially H. diminuta in mice and rats, which will be referred to below.