Szmuness, W. (New York Blood Center, 310 E. 67th St., N. Y., N. Y. 10021), R. Pick and A. M. Prince. The serum hepatitis virus specific antigen (SH): a preliminary report of epidemiologic studies in an institution for the mentally retarded. Amer. J. Epid., 1970, 92: 51–61.-SH antigen was detected in 35.1% of patients with Down's syndrome and in 17.2% of a matched sample of patients with other forms of mental retardation. One-half of the antigen carriers had biochemical signs of chronic active anicteric hepatitis. The duration of the carrier state appears to be longer in Down's syndrome patients. Statistical associations between the occurrence of the carrier state and different risk factors have been established. Among these, age at the time of exposure appeared to be the most important. Certain epidemiologic conditions peculiar to this population appear to favor nonparenteral transmission of SH virus(s). Due to limitations in sample size and design of the study, these hypotheses require further evaluation in other populations.