Qualitative evaluations of buccal smear specimens have indicated an unusually high incidence of triple-X females in a hospitalized schizo­ phrenic population. Specimens from adult prisoners have also indicated an unusually high incidence of triple-X females. Studies of a population of confined juvenile offenders, on the other hand, have indicated an unusually high incidence of one-X females. No unusual indications were observed in a population of "normal" volunteer females. The data and their implications are discussed in context with previous observations. ACKNOWLEDGMENTS This study was made possible primarily by research grants from the Scottish Rite Committee on Research in Schizophrenia, The National Association for Mental Health, Inc. Additional support was provided by a grant from the National Institutes of Health, GRS-05563. The study has been supported by the State of Ohio, Department of Mental Hygiene and Correction, Division of Mental Hygiene. The author is particularly indebted to Edward N. Hinko, M.D., Regional Director of Research, whose advice and help made the present study possible. Invaluable cooperation and help have been received from the following administrators and their staffs: F. A. Lingl, M.D. (Cleve­ land Psychiatric Institute); Martha Wheeler (Ohio Reformatory for Women); M. B. McLane (Scioto Village); M. B. Holmes, M. D., and S. Caruso, M. D. (Massillon State Hospital); G. F. Ogram, M. D. (Athens State Hospital); C. Waltner, M. D. (Woodside Receiving Hospital); A. Mako, M. D. (Fairhill Psychiatric Hospital); and W. G. Stover, M. D.