The most common cause of enlarged testicles is an infection that causes inflammation of the epididymis, a coiled tube behind each testicle. Typically, there’s pain in the testicles, often accompanied by a red and swollen scrotum. Other causes of testicular enlargement include painless and usually harmless cysts or excess fluid in the membrane surrounding the testicles, a condition known as a hydrocele . Varicose veins, in which one of the veins that drains the testicles becomes dilated, can also cause enlarged testicles. Cancer of the testicle mainly affects young men, so testicular enlargement in a man under 30 should be examined as soon as possible. It may indicate the presence of testicular cancer or a pre-cancerous condition. But regardless of age, prompt examination is recommended for anyone with an enlarged testicle. Treatment may include antibiotics, pain killers, ice packs, elevation of the groin area, or in some cases, surgery. For more information on enlarged testicles, talk to a physician or urologist.