This collection of articles, edited by D. Wakelin and D. Walliker include: Genetic variability in parasites and host-parasite interactions; Host genetics and infectious disease; T cell and cytokine basis of host variability in response to intestinal nematode infections; The role of MHC- and non-MHC-associated genes in determining the human immune response to malaria antigens; Influence of host and parasite genotypes on immunological control of Theileria parasites; Genetic susceptibility to leishmanial infections: studies in mice and man; Genetic susceptibility to malaria and other infectious diseases: from MHC to the whole genome. This volume is the specially commissioned supplement to the journal Parasitology, volume 112.