We report herein a case of ureteral obstruction associated with pelvic inflammatory disease in a long-term intrauterine contraceptive device (IUD) user. A 62-year-old woman presented with a 2-week history of left flank pain and high fever, but no abdominal pain. She had forgotten the use of an IUD. Retrograde pyelography showed a stricture in the lower third of the left ureter. Magnetic resonance showed swelling of the uterus wall and left parametria, but did not reveal the presence of an IUD. Subtotal hysterectomy, bilateral salpingo-oophorectomy and left nephronureterectomy was performed. The IUD was then found in the uterine cavity. The results of pathological and bacteriological findings for Actinomyces infection were negative. Therefore we diagnosed this case as ureteral obstruction associated with pelvic inflammatory disease. Ureteral obstruction associated with pelvic inflammatory disease in a long-term IUD user is extremely rare.