Acute idiopathic scrotal edema (AISE) is characterized by an unknown cause, a self-limiting acute scrotal edema and erythema that resolves without sequelae. It is important to differentiate other acute scrotal swelling from AISE in which sonography can help establishment of the diagnosis and lead to the avoidance of surgical exploration. We report the sonographic findings of two cases with AISE and review the literature on this condition. Ultrasonographic findings of AISE were marked echogenic thickening of the skin of the scrotum and adjacent subcutaneous layers. However, the testes and epididymes were normal and blood flow on Doppler ultrasonography and testicular scintigraphy was not remarkable. Follow-up sonography after 24 hours showed normalized scrotal wall thickening in one case.