Twenty-seven girls with premature pubarche were studied by ultrasonographic and color Doppler analyses to determine the incidence of polycystic ovaries (PCO), to longitudinally assess their evolution, and to search for any hormonal correlation. The girls were submitted to auxological, clinical, and hormonal evaluation, and 21-hydroxylase deficiency was ruled out by an ACTH test. Furthermore, the girls underwent ultrasonographic and color Doppler ovarian and uterine analyses. Among girls with premature pubarche, the prevalence of PCO was 41%. Advanced skeletal maturation, tall stature, and increased hair distribution were constant in these patients. In patients with ultrasonographic and color Doppler evidence of PCO, the ovarian volume, the number of small-sized subcapsular follicles, the stromal echogenicity, and the ovarian stromal vascularization progressively increased during the study. In the whole studied population, ovarian volume correlated with the number of small-sized follicles (r = 0.719; P < 0.0001). Furthermore, a slight and inverse correlation has been found between ovarian volume and ovarian stromal artery pulsatility index (r = -536; P = 0.048). In conclusion, we affirm that PCO are greatly represented among girls with premature pubarche and progressively evolve.