BACKGROUND: In the pre-microbiological era, it was widely accepted that diseases, today known to be infectious, were hereditary. With the discovery of microorganisms and their role in the pathogenesis of several diseases, it was suggested that exposure to the pathogen was enough to explain infection. Nowadays, it is clear that infection is the result of a complex interplay between pathogen and host, therefore dependant on the genetic make-up of the two organisms. Dermatology offers several examples of infectious diseases in different stages of understanding of their molecular basis. In this review, we summarize the main advances towards dissecting the genetic component controlling human susceptibility to infectious diseases of interest in dermatology. Widely investigated diseases such as leprosy and leishmaniasis are discussed from the genetic perspective of both host and pathogen. Others, such as rare mycobacterioses, fungal infections and syphilis, are presented as good opportunities for research in the field of genetics of infection.