Plasma levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), dehydroepiandrosterone (DHA), dehydroepiandrosterone-sulphate (DHA-S), 17-hydroxyprogesterone (17P), androstenedione (A), testosterone (T), dihydrotestosterone (DHT) and estradiol (E2) were measured in basal conditions in eleven young women from 16 to 25 years of age characterized by delayed puberty. The gonadotropin response to LHRH (50 microgram iv) was also tested in these cases. The results, as far as gonadotropins and E2 are concerned, indicate that delayed pubertyin girls is a heterogeneous disorder: an impairment in the negative feedback between E2 and FSH coexists with a reduced ovarian response to endogenous gonadotropins. All cases showed evidence of a more or less pronounced delayed adrenarche, which was demonstrated by the markedly reduced levels of DHA-S and DHA (with the exception of this latter steroid in two cases with idiopathic hirsutism). Furthermore, the very low plasma progesterone (P) levels in all cases suggest the existence of impaired delta 5 - delta 4 isomerase activity in the adrenal cells. Despite the low levels of A and T, DHT is within the upper limits of the normal range in all cases.