Rubella is a viral exanthematous infectious disease caused by Rubella virus. The illness follows a typically benign clinical course with rare complications and is subclinical in a large proportion of cases. Symptomatology is generally mild, characterized by fever, malaise, a maculopapular rash of 3 to 5 days duration and possibly coryza and conjunctivitis. The disease is usually accompanied by lymphadenopathy. Infection confers lifelong immunity. This assay determines Rubella immune status in individuals. A positive result indicates prior exposure to the virus or response to vaccination. Presence of IgG antibody does not exclude the possibility of ongoing infection. In these cases IgM antibody measurement is indicated.