This study was performed to determine the high-resolution sonographic findings of ovarian granulosa cell tumors (GCTs) and to correlate the sonographic findings with the pathologic findings. A retrospective review of sonographic findings was conducted on 16 patients with surgically proven ovarian GCTs. Patients' ages ranged from 10 to 64 years (mean, 37.7 years). We evaluated the sizes and morphologic appearances of the ovarian tumors. The blood flow patterns of the tumors were assessed with Doppler sonography (n = 6). Sonographic findings were compared with pathologic findings. The maximal diameters of the masses were 2.0 to 15.4 cm (mean, 8.2 cm). The morphologic appearances of the masses were classified into 3 patterns; solid and cystic (n = 10), solid with a sponge form appearance (n = 4), and entirely solid (n = 2). The measured resistive index and pulsatility index of the solid portions were 0.23 to 0.5 and 0.26 to 0.62, respectively. Pathologic diagnoses of 13 adult ovarian GCTs and 3 juvenile GCTs were obtained. The solid and cystic masses had GCTs with macrofollicular and microfollicular patterns pathologically. The solid masses with a sponge form appearance had prominent hemorrhagic necrosis and diffuse proliferation of granulosa cells with trabecular and microfollicular patterns. The entirely solid masses had diffuse cellular proliferation with a trabecular pattern without cystic changes or hemorrhagic foci. Sonographic findings of ovarian GCTs included solid and cystic masses, solid masses with a sponge form appearance, and entirely solid masses, and the sonographic findings correlated well with the histopathologic findings.