While the incidence of many bacterial sexually transmitted diseases appears to be decreasing, the complications and frequency of viral sexually transmitted diseases in developed countries has increased over 10-fold in the last decade. Since 1975 genital herpes simplex virus infections have increased at a rate of 12% in the United Kingdom. Significant advances in our understanding of the epidemiology, natural history, and therapy of symptomatic genital herpes has occurred in the last 5 yr. In order to properly utilize this information, however, more widespread availability of laboratory diagnostic testing for herpes simplex virus is needed. The availability of tissue culture isolation facilities for herpes simplex virus has expanded to many community hospitals. More importantly, rapid assays to detect herpes simplex virus using monoclonal and polyclonal antibodies in enzyme-linked immunosorbent assay and immunofluorescent assays and/or detection of herpes simplex virus deoxyribonucleic acid by hybridization methods have also been developed. Recent studies indicate that these assays approach the sensitivity of viral isolation when samples from mucocutaneous lesions are taken. These rapid assays have also allowed clinicians to more rapidly diagnose serious herpes simplex virus infection such as neonatal herpes and to institute antiviral therapy earlier in the course of disease. Although the specificity of these assays in high prevalence populations appears excellent, few studies have evaluated these assays in populations where the prevalence of herpes simplex virus is low. Rapid assays for herpes simplex virus also appear to have decreased sensitivity (less than 60%) in detecting asymptomatic excretion of herpes simplex virus from the lower genital tract.(ABSTRACT TRUNCATED AT 250 WORDS)