The accuracy of Doppler sonography in the evaluation of testicular torsion was tested in 65 boys (aged 0-18 years) with acute scrotal pain or swelling. All patients underwent pulsed Doppler sonography of both testes, followed by scintigraphy (n = 16) and/or surgery (n = 34) and a close clinical follow-up for 4-8 months (n = 31). Color Doppler sonography was performed in 29 patients. The testicular artery was deemed patent if Doppler shifts from branches within the parenchyma could be found. Surgery revealed 19 cases of testicular torsion, 17 of which were diagnosed with Doppler sonography. There were six technical failures, in which no signals could be found on either side. In four boys, no color signals were obtained in either testis but subsequent examination with a mechanical sector scanner and pulsed Doppler sonography yielded arterial signals. Doppler sonography was successful in 59 of 65 boys (91%) and yielded a sensitivity of 89% and specificity of 100%. Pulsed Doppler sonography with mechanical sector scanners was more sensitive than color Doppler sonography. Intermittent torsion was missed both with Doppler sonography and scintigraphy.