Serologic techniques for the detection of antibodies to rubella virus provide the approach of choice for laboratory diagnosis of acute and congenital rubella infections and for the determination of rubella immunity status. Rubella serodiagnostic tests currently being used in clinical laboratories are described in this review. Advantages, limitations, and relative sensitivities and specificities of these tests are presented. The reactivity and specificity of rubella antibody tests have been shown to vary from laboratory to laboratory and from one manufacturer's kit to another. The need is clearly apparent for a universally accepted reference standard that will allow sensitivities and alternative assays to be compared directly and a meaningful immune cutoff level to be established. Incorporating such standards into the available rubella tests would eliminate much of the diagnostic uncertainty associated with rubella infections during pregnancy.