We performed pelvic ultrasound assessment in 104 patients with Turner syndrome aged 0.2 to 17.4 years; 69 had the 45,X karyotype and 35 had variant karyotypes. Ovarian appearances were classified as "streak" (n = 70, including 30 patients in whom no ovary could be seen) or "nonstreak" (n = 34). The nonstreak ovaries ranged from small glands, sometimes containing minute cysts, to ovaries indistinguishable from those which are normal for age. Nonstreak ovaries retained a range of function, as evidenced in some cases by spontaneous breast development and uterine enlargement. The proportion of nonstreak ovaries followed a U-shaped pattern, with a nadir from 4 to 10 years; this follows the known biphasic pattern of luteinizing hormone and follicle-stimulating hormone secretion. Only those patients with karyotype variants in which the long arm of the X chromosome was retained fared better than those with the 45,X karyotype.