Antigenically the respiratory syncytial virus (RSV) is of two types: A and B. Five structural proteins express virus type differences. Antigenic and genetic differences among individual strains of the same virus type are classed accordingly by monoclonal antibody reactivity into antigenic subtypes; for nucleotide sequence and restriction maps of individual gene polymerase chain reaction products they have different genetic categories: SHL 1-6, NP 1-6. Still unproved is the association between the virus-caused clinical picture severity and virus type. One type or both may be the causative agents of an RSV epidemic. Between 1988 and 1994, both types of RSV strains circulated in Central Europe, as well as the different subtypes within each type; type A, particularly subtype A1, was absolutely dominant. RSV isolates were of genotypes SHL 2, SHL 1/3/4, SHL 5, NP 1. They occurred in the same order as the genotypes shown in the rest of Europe and the world.