THE EPIDEMIC of rubella which occurred in 1964 was the largest which the United States has experienced in more than 20 years.1In Connecticut a record number of cases was reported, more than 40,000 in a population of some 2,500,000, and the actual number was probably greatly in excess of this figure. Inevitably, in such a large outbreak, many young women were infected in the first trimester of pregnancy, and many infants with stigmata characteristic of the rubella syndrome have been born subsequently. We have investigated several aspects of the rubella problem, including a questionnaire survey to determine the incidence of the disease in pregnant women in the New Haven, Conn, area. Clinical observations have been made on infants with the rubella syndrome, and virologic studies have been carried out on products of conception obtained at induced abortion, on various specimens collected from babies born with congenital malformations characteristic