We present a patient with unilateral, spontaneous, late leg swelling that developed 4 years after total hip arthroplasty. The etiology was the compression of the internal iliac vein by a voluminous iliopsoas bursitis caused by polyethylene debris. The expansive lesion was detected by ultrasound, arthrography, and magnetic resonance imaging. An ultrasound-guided aspiration provided transient relief of the patient's symptoms. The patient later required surgical excision through an abdominal approach. A second recurrence was detected and treated with revision surgery. We present the diagnosis and the treatment of this rare cause of late, unilateral leg swelling after total hip arthroplasty together with a review of the literature.