We report an unusual case of a pseudoaneurysm of the superior gluteal artery as a complication of bone marrow biopsy. A 51-year-old man presented with sciatic pain and foot drop after undergoing bone marrow biopsy and was initially diagnosed as having degenerative disc disease based on his past medical history. Pelvic magnetic resonance imaging (MRI) revealed a large heterogeneous mass suggestive of a neurogenic tumor, but pulsatile blood was instead encountered during computed tomography (CT)-guided needle biopsy. Subsequent workup established the diagnosis of a superior gluteal artery pseudoaneurysm, which was treated with coil embolization, followed by surgical evacuation of the hematoma, which relieved his sciatic pain. However, the patient continues to have a persistent foot drop. Gluteal artery pseudoaneurysms are exceedingly uncommon but should be considered in the workup of a patient with gluteal pain or sciatic nerve palsy following trauma or medical procedures in the gluteal region.