The majority of cases of acute scrotum are due to one of these three causes: trauma, torsion and inflammation. Acute scrotum syndrome of any origin always merits immediate evaluation to prevent testicular function and chronic irreversible complications. Correct differential diagnoses between these conditions are mandatory because an incorrect diagnosis could lead to catastrophic consequences. Often, physical examination is not sufficient to avoid suspicious conditions that require surgical correction and then imaging. High-resolution ultrasound is the imaging modality of choice for the examination of superficially located scrotal sac and its contents. Greyscale ultrasonography in combination with colour or power Doppler imaging is a well-accepted technique for assessing scrotal lesions and testicular perfusion. In this chapter, clinical features, greyscale and colour Doppler ultrasonographic (US) appearance of testicular torsion, trauma and inflammation are described.