Acute epididymitis has a sudden onset with swelling, fever, and pain in the epididymis (may involve outwardly to the groin, lower back, and lower abdomen), local and spermatic cord coarseness and pressure, and often syringomyelia; the inflammation subsides after about 2 weeks, leaving a fibrous hard node. If symptoms persist, the testicular blade tumor needs to be removed. In treatment, rest, scrotal support, cold capsule, cold compresses, analgesia, suspension of sexual life, application of antibiotics and spermatic cord closure, with indwelling catheter must be removed, has formed an abscess then incision and drainage. (I) Clinical manifestations: sudden onset, high fever, elevated leukocytes, distension and pain in the scrotum on the affected side, sinking sensation, pulling pain in the lower abdomen and inguinal region, aggravated when standing or walking. The affected epididymis is swollen and there is obvious pressure pain. When the inflammation is large, both the epididymis and the testis are swollen and the boundary between them is indistinct to the touch. The spermatic cord on the affected side is thickened and there is also pressure pain. Usually, the acute symptoms can gradually subside after a week. (B) Diagnosis and Differential Diagnosis The diagnosis of this disease is not difficult based on history and physical signs, but attention must be paid to differentiate it from testicular torsion. Testicular torsion has a rapid onset, the testicle is enlarged and fixed, and it cannot move within the scrotum, and elevating the scrotum cannot reduce the local pain. Sometimes epididymal tuberculosis and testicular tumor may appear similar to acute epididymitis, so attention should also be paid to differentiate them. (C) Treatment Acute epididymitis should be treated with proper rest and given antibacterial agents and general analgesics. Local hot compresses, physiotherapy and scrotal brace should be used to hold up the scrotum. If there is abscess formation, incision and drainage are required.