The sonographic findings in 19 cases of surgically proven torsion of the ovary are described. In all cases the affected ovary was markedly enlarged; in 32% of cases a small amount of fluid was detected in the cul-de-sac. More significant in terms of specificity was the demonstration in 14 (74%) of the 19 cases of small cystic structures scattered around the periphery of the organ. Sonographic demonstration of these structures, presumably prominent follicles, can suggest the preoperative diagnosis of ovarian torsion.