OBJECTIVE. Our objective was to correlate ovarian and uterine sonographic variables with age and pubertal status in a sample of healthy girls. SUBJECTS AND METHODS. In this prospective study, 139 consecutive patients between I and 13 years old (mean +/- SD, 6.0 +/- 3.4 years) underwent sonography and hand radiography (for bone-age determination). Pubertal development was classified according to Tanner stages (prepubertal, 5.0 +/- 2.7 years [n = 117]; pubertal, 11.2 +/- 1.2 years [n = 22]). Uterine and ovarian longitudinal, transverse, and anteropostetior diameters were measured. Uterine fundal-cervical ratio was determined. Ovaries were morphologically classified as homogeneous. paucicystic, multicystic, macrocystic, and presenting isolated cysts. A p value less than or equal to 0.05 was considered significant. RESULTS. The uterus was identified in 96% of the patients (mean, 6.1 +/- 3.4 years). One ovary was visible in 93% (mean, 6.2 +/- 3.4 years), and both ovaries, in 81% (mean, 6.5 +/- 3.3 years). Neither ovary was visualized in 10 girls (mean, 2.5 +/- 2.2 years). Uterine parameters and ovarian volume were smaller in patients without thelarche (p < 0.0001). Mean ovarian and uterine size was smaller in girls until 8 years, intermediate between 9 and I I years, and larger after 12 years (p < 0.0001). Chronologic age, bone age, and Tanner stage were correlated even before 7 years. Patients with and without thelarche presented different ovarian morphology (p = 0.0 1), CONCLUSION. Uterine and ovarian growth was associated with age and puberty. Uterine length presented the best correlation with age. Multicystic ovaries seemed to be correlated with normal or premature pubertal stimuli.