Thank you for asking Healthcare majic. My name is Dr Ehsan Ullah & I have gone through your query. i don t have info regarding your age and pain status. well, there are different causes of scrotal swelling depending upon its characteristic one of the feature is Pain Painful scrotum and tender(painful) testicular -Epididymitis (Epididymitis is an inflammation of the coiled tube (epididymis) at the back of the testicle that stores and carries sperm) -Orchitis (inflammation of one or both testicles) -Testicular torsion -Trauma – e.g. hematocoele Painful Scrotum and non tender testis Incarcerated hernia (a condition in which herniated tissue is trapped in a hernial sack.) Insect bite Rash while the painless testicular swelling causes are -hydrocele which is accumolation of fluid -vericocele which is enlargement of the veins within the loose bag of skin that holds your testicles (scrotum) -spermatocele which is an abnormal sac in a part of testis called epididymis -inguinal hernia -testicular tumors which becomes painful in rapidly growing stages there is also a list of other causes too but all you need is to visit your Physician as such testicular swelling need a detailed history along with relevant examination and at times Labs for further evaluation. Hope this may help you. Let me know if anything not clear. Thanks.