This article presents a unique case of posttraumatic extrapelvic endometriosis presenting as a gluteal mass causing cyclic sciatica. A 38-year-old woman presented with an enlarging right buttock mass over the previous 6 years. She also had symptoms of radicular pain referred to the right leg and foot with sitting and daily activity. Four years prior to noticing the mass, she sustained a gunshot wound through the lower abdomen while 5 months pregnant. Excisional biopsy of the gluteal mass revealed endometrioma. Sciatica is a common and painful disorder that is believed to have an incidence of 40% in the adult population. Sciatica is most often due to intraspinal pathology affecting the lumbar nerve roots. There are many recognized extraspinal etiologies for sciatica in the literature including aneurysms, sciatic hernia, abcess, neoplasm, trochanteric wire, piriformis syndrome, ischial fracture, a posteriorly flexed uterus, and even an intrauterine device following uterine perforation. Similarly, endometriosis is a gynecologic condition that represents a significant health problem for women of reproductive age as it occurs in up to 50% of premenopausal women and 71% to 87% in women with chronic pelvic pain. Although rare, endometriosis has a well known ability to migrate outside of the abdominal cavity and proliferate ectopically under the control of systemic estrogen.