The purpose of the present study was to determine whether the demasculinizing and feminizing effects of prenatal stress (i.e., stress applied to the mother during pregnancy) in rats reported previously are mediated by activation of the maternal pituitary-adrenal axis. Neither whole-body restraint, with or without hyperthermia, nor ACTH treatment during the last third of gestation had any reliable effect on masculine or feminine sexual behavior in male Sprague-Dawley offspring, although these treatments produced maternal pathology and evidence of maternal adrenocorticoid release. Significant littermate similarity was found for almost every morphological and behavioral measure. Failure to control for the litter variable may account for many previously reported effects of prenatal stress on sexual behavior in rats. The discrepancy between the present and earlier findings is discussed in terms of methodological and theoretical considerations.