THE isolation of rubella virus1 , 2 in 1961 opened a period of remarkable progress in studies of the virus,3 the disease4 and, recently, experimental vaccines for preventing the disease.5 , 6 Comparable progress has not been made in the development of simple, rapid serodiagnostic methods. Although virus neutralization,7 , 8 fluorescent antibody9 and complement fixation10 are being employed only the complex and time-consuming neutralization test has been capable of furnishing the epidemiologist with fully reliable information regarding rubella immunity. The purpose of this paper is to report specific rubella-virus hemagglutination and the development of a hemagglutination-inhibition test for antibody assay. Materials and Methods Virus Strains . . .