Many species of mites are of agricultural and veterinary importance to human. The bacterial symbiont Cardinium is assumed to be widespread and involved in manipulating its mite host's reproduction. We investigated Cardinium infections in phylogenetically diverse mite species based on published data. Cardinium was reported in 45 mite species, representing 3 orders and 14 families. Some Cardinium strains can influence their mite hosts' reproduction via two strategies: cytoplasmic incompatibility and feminization. The phylogeny of the examined mites was well resolved based on the 18S rRNA gene, whereas Cardinium phylogeny was not completely concordant with its associated host phylogeny, raising the possibility that horizontal transmission of Cardinium has occurred among species. In addition, Cardinium phylogeny was associated with the ecology of the hosts. Cardinium cooperating with other endosymbionts influences the ecology and evolution of its host.