This review focuses on the principal strategies for conviviality in mice parasite relationships, specially in those genetically determined, and discussed as: a) Innate susceptibility of the host to the parasite; b) Specificity of the parasite for the host, and c) Susceptibility derived from genetic interactions between host and parasite. It is concluded that susceptibility is regulated by multiple genetic facts from both host and parasite, which can interact and modify each other, making each instance of host-parasite relationship unique.