PURPOSE: To describe the sonographic findings of inguinal herniation of the ovary. MATERIALS AND METHODS: Forty-five girls aged 1-12 (mean, 4.7) months with a groin mass underwent sonographic examination, and in seven of the 45, inguinal herniation of the ovary was detected, and confirmed at surgery. Gray-scale and color Doppler sonographic examinations were performed to evaluate the size, echo pattern, and blood flow of the mass. Sonography of the pelvis and contralateral groin was also performed. RESULTS: In all seven cases, sonography revealed an oval-shaped complex mass 15-25 mm in maximal diameter and composed of heterogeneous hypoechoic portions and one to seven small internal cysts, each 2-9 mm in diameter. Blood flow was observed in all cases, though was subtly decreased in one. In two there was associated herniation of the salpinx, and in two others, incarceration. In four, contralateral inguinal hernia was present. CONCLUSION: Sonographic findings of an oval-shaped heterogeneous hypoechoic mass with internal small cysts, present in the groin, indicate inguinal herniation of the ovary.