Dexamethasone (DEX) administration to the pregnant woman has become the treatment of choice for the prevention of genital masculinization in female fetuses affected with congenital adrenal hyperplasia (CAH). Although no somatic teratological side effects have been found to date, recent animal research has shown adverse effects of glucocorticoids on brain structures such as the hippocampus, raising concerns about possible functional side effects of DEX on human development. The current survey of 487 children, 1 month to 12 yr of age, focused on cognitive and motor development. The mothers of 174 prenatally DEX-exposed children (including 48 with CAH) and 313 unexposed children (including 195 with CAH) completed four standardized developmental questionnaires about their children. None of the comparisons of prenatally DEX-exposed children and unexposed controls was significant. Among the DEX-exposed children, increased duration of DEX exposure was correlated with significantly fewer developmental delays on three variables of one of the questionnaires, but none of the correlations reached significance, when Bonferroni corrections for multiple correlations were used. With the methods used, we were unable to document any adverse effects of early-prenatal DEX treatment in the doses recommended for the treatment of pregnancies at risk for CAH on motor and cognitive development.