Isolated spermatic vein thrombosis is an uncommon pathology, mostly involving left side. These patients present with acute scrotal symptoms, and can be misdiagnosed as testicular torsion or incarcerated inguinal hernia. At this point, Doppler ultrasound (US) plays critical role for the prompt and correct diagnosis of this rare clinical entity. Herein, a 54year-old man having left sided testicular enlargement and tenderness with an unremarkable etiology was reported as a rare case of isolated spermatic vein thrombosis which could easily be diagnosed by colour Doppler US.