Over a three-and-a-half year period, 26 children with precocious pubarche or other forms of sexual precocity were studied. All had plasma steroid patterns analyzed, in most cases both before and after stimulation with ACTH. 17 of the children had elevation of the delta 5-steroids dehydroepiandrosterone and 17-OH-pregnenolone and their individual results are presented. Five of these children were diagnosed with probable late-onset 3 beta-HSD deficiency. The difficulties in differentiating this entity from idiopathic premature adrenarche are emphasized.