The purpose of this study was to assess the diagnostic value of ultrasonography for the detection of twisted vascular pedicle in ovarian torsion and to verify whether the blood flow alterations in the twisted vascular pedicle on color Doppler sonography can predict the viability of adnexal structures. In 28 of 32 patients with surgically proved torsion, the twisted vascular pedicle was detected preoperatively by ultrasonography, which shows a diagnostic accuracy of 87%. Arterial and venous flows were present in the twisted vessels on color Doppler sonography in 16 of 28 patients with a visible twisted vascular pedicle. In 11 patients who underwent adnexectomy, the pathologic findings revealed nonnecrotic ovaries in 10 patients. Untwisting of the twisted vascular pedicle was performed in five patients, and follow-up ultrasonography showed normal follicular development and ovulation. All 12 patients who showed no blood flow within the twisted vascular pedicle had necrotic ovaries. In conclusion, identification of the twisted vascular pedicle through ultrasonography is suggestive of ovarian torsion, and color Doppler sonography could be helpful in predicting the viability of adnexal structures by depicting blood flow within the twisted vascular pedicle.