We studied eight children (seven girls and one boy, of whom three are siblings) with accelerated growth, premature pubarche and/or hirsutism between the ages of 7 and 9.5 years. These patients were studied for the presence of adrenal steroidogenic defect by adrenocortico tropic hormone (ACTH) stimulation testing (Cortrosyn, 0.25 mg iv bolus dose). Baseline and stimulated 17-hydroxypregnenolone (delta 5-17P), 17-hydroxyprogesterone (17-OHP), dehydroepiandrosterone (DHEA), androstenedione (delta 4-A), testosterone, and cortisol levels were measured. Six children, including three siblings, were diagnosed with a mild form of 3 beta-hydroxysteroid dehydrogenase deficiency based upon the elevated response of serum delta 5-17P and the elevated ratio of delta 5-17P/17-OHP and of DHEA/delta 4-A to ACTH stimulation. Thus, a mild form of 3 beta-hydroxysteroid dehydrogenase deficiency may not be uncommon in children with accelerated growth, premature pubarche and/or hirsutism and routine assay of delta 5-steroid metabolites should be generally available.