Epididymitis and orchitis normally co-exist with isolated epididymitis being more common than an isolated orchitis. Epididymo-orchitis (EO) can be acute (less than 6 weeks' duration), sub-acute, or chronic if persisting for more than three months and typically presents with testicular pain and swelling. Sexually transmitted infection (STI) is the most common cause in younger men and urinary tract pathogens are the more common culprits in older men. The most common pathogens in the under 35s are N gonorrhoeae and C trachomatis and E coli is the most common cause of acute epididymitis in the over 35s. Acute testicular torsion is the most important differential diagnosis of acute testicular pain especially in younger men. If there is any suspicion of testicular torsion, the patient should be referred to secondary care immediately as surgery is required within four to six hours. Patients who are in severe pain or systemically unwell should be referred for analgesia, IV antibiotics and hydration. Examination of a patient with acute EO classically reveals a swollen, tender testis with swelling of the epididymis which starts at the lower pole and moves up towards the head of the epididymis at the upper pole of the testes. UTI in men is often associated with bladder outflow obstruction. So it is important to examine the bdomen for a palpable bladder and to perform a digital rectal exam to check for BPH, prostate cancer, constipation and prostatitis which can also cause EO.