Enteroviral infections are potentially serious in man causing a variety of syndromes and a viraemic phase is probable in most patients. However, virological diagnosis is usually indirect by isolation of the agent from throat or stools when possible, and/or slow due to the need to titrate antibodies in paired sera. Because of its high sensitivity the polymerase chain reaction (PCR) offers the possibility of rapid detection of even low-grade viraemia. We have developed a 2-step PCR procedure adapted for enteroviruses and applied it to stored sera from patients with enteroviral meningitis. The acute sera from 7/12 patients were positive but the 4 convalescence sera tested, 2 of which had been positive at the acute phase, were negative. The assay should now be tested prospectively on serum and cerebrospinal fluid and could be developed for routine diagnosis.