Anencephalus, hydrocephalus, and spina bifida constitute a significant proportion of the more serious congenital malformations. A better understanding of the epidemiology of these disorders may clarify the role of environmental and genetic factors in etiology and possibly lead to successful preventative measures. In this report, the results of a survey of anencephalus, hydrocephalus, and spina bifida in Charleston, S.C., are presented, and literature pertaining to the epidemiology of these disorders is reviewed. Survey Method in Charleston, S.C. Hospital and clinic records, autopsy reports, and mortality records of stillbirths and deaths were studied for the 10-year period January, 1946, through December, 1955. Also the records of the 2 neurosurgeons and the neurologist in the community as well as records of the Crippled Children Program of the State were made available to the investigator. All records with a diagnosis of anencephalus, hydrocephalus, spina bifida, and other myelodysplasias were noted. Not included in