For many years a substitute cell line has been sought to replace monkey kidney cell cultures for the diagnosis of enterovirus infections. Reports by various workers have shown that the RD cell line, derived from a human rhabdomyosarcoma, will support the replication of most of the prototype strains of enterovirus. The present study shows that, with the exception of the group B coxsackieviruses, RD cells are more sensitive than cynomolgus monkey kidney cultures for the isolation of a wide variety of enteroviruses from clinical specimens. Since regular access by many diagnostic laboratories to supplies of primary cell cultures is often difficult because of distance from source or cost factors, a simple cell culture system is proposed which should prove useful for the diagnosis of most of the important enterovirus infections.