Present biodiversity is shaped through species diversification and extinction in the evolutionary history. Therefore, phylogeny, as a representative of species evolutionary history, can lend insight towards examining current biodiversity patterns, including the distribution and diversity of mammals and of their parasites. Phylogenetic diversity (PD) has been proposed as an important measure of biodiversity because PD incorporates the number of species and the genetic and functional diversity of the species. Phylogeny of host species might also be associated with the distribution and diversity of parasites, many of which are relevant to wildlife conservation. My dissertation research focuses on evaluating phylogenetic information in predicting broad-scale patterns of distribution and diversity of mammals and their parasites. I combined multiple global comparative data sets compiled across large taxonomic and spatial scales, and conducted phylogenetic analyses to investigate two central topics in mammal conservation biology: (1) global distribution patterns of mammalian diversity, and (2) the parasite distribution and diversity in free-ranging mammals. I first compared phylogenetic diversity and species richness in predicting a third measure of biodiversity, the trait diversity of mammals. I then searched for geographic regions where potential loss of phylogenetic diversity is higher than expected by the number of threatened mammal species and investigated mechanisms causing such extra loss. Next, I assessed the importance of host phylogeny, in comparison with other host ecological traits, in predicting the number of parasite species infecting a host species. I also compared the phylogenetic relatedness between host species, host ecological similarity and geographic range overlap, for predicting the parasite species assemblages between host species. Overall, my research has demonstrated that phylogenetic information is essential for quantifying mammal biodiversity and estimating potential loss in mammal biodiversity. Furthermore, knowledge of host phylogeny often provides the most important predictors, in comparison with host ecology, for the distribution and diversity of parasites among mammal hosts.