Acute scrotal pain makes up approximately 0.5% of all complaints presenting to an emergency department. Some of the most com-mon diagnoses for this complaint are testicular torsion and epididymitis. Misdiagnosing testicular torsion can lead to organ loss,cosmetic deformity, and compromised fertility. Modem ultrasound examination of the scrotum is the test of choice for acute scrotal pathology and yields high accuracy compared with surgical exploration. A key component of the testicular examination is use of power and spectral Doppler ultrasonography. Examination of the acute scrotum should not be undertaken unless Doppler capability is available because the evaluation of blood flow is such an important part of diagnosis of testicular torsion, orchitis, epididymitis,trauma, and hemorrhage into a mass.