A 65-year-old man with a left uncemented total hip arthroplasty performed 11 years previously was admitted with a history of progressive low back pain, left hip pain, and sepsis that had begun 6 months earlier. On physical examination, a gross, fluctuant mass was palpated in the left thigh. A computed tomography (CT) scan revealed a 6.5 x 3 cm left retrofascial psoas abscess communicating with the hip joint. The patient underwent irrigation and débridement of the hip with removal of the components. The psoas abscess was drained through the iliopsoas bursa. A residual psoas abscess was drained percutaneously under CT guidance. Cultures isolated Escherichia coli, and the patient responded to 6 months of ciprofloxacin therapy. After 1 year, the patient had no evidence of infection. Pathways of infection spread, diagnosis, and treatment of a patient with this rare association are discussed with a review of the literature.