An increased incidence of spina bifida among live-born infants in Vermont during 1962 has been observed and documented. The average incidence for this congenital anomaly during the period 1952-1961 was 99 per 100,000 live births; in 1962 it increased to 232 per 100,000 live births. This is the second report of such an occurrence in the United States during 1962. Epidemiologic studies failed to reveal any clues as to a possible teratologic agent.