A new Vi-phage-type of Salmonella typhi, type F(7), isolated in Poland in 1963, is described. The homologous typing phage was prepared from phage F(1). The new Vi-phage-type belongs to the F group and its "precursor" is type F(1). No temperate type-determining phage has so far been isolated from this phage-type. The homologous typing phage F(7) is a phenotypically modified host-range mutant of Vi-phage II; its phenotype is F(1) and the genotype is that found in phage 35, and is related to phage C(11).