Iliotibial band friction syndrome presents with lateral knee pain usually in runners. When conservative treatment fails, surgical lengthening, or Z-plasty, can provide symptomatic relief. This retrospective study evaluated the long-term results of iliotibial band Z-plasty for chronic iliotibial band friction syndrome in a consecutive series of patients. Inclusion criteria were failed nonoperative treatment for symptomatic iliotibial band friction syndrome for at least 3 months, minimum age of 17 years, and closed growth plates. Exclusion criteria were history of significant trauma, prior knee surgery, lateral compartment pathology, and anterior or posterior cruciate ligament instability. Postoperative evaluation included annual physical examination consisting of Tegner, Lysholm, Cincinnati, and International Knee Documentation Committee (IKDC) activity scores. Of an initial group of 11 patients, 8 were evaluated an average of 75.6 months postoperatively (range: 59-97 months). Average length of preoperative symptoms was 15.6 months (range: 3-36 months), and average length of nonoperative management was 6.9 months (range: 3-24 months). Postoperatively, mean Cincinnati score was 82.9 (range: 55-95), Tegner score was 4.4 (range: 2-7), Lysholm score was 88.6 (range: 57-100), and IKDC activity score was 2.6 (range: 1-4). No adverse events occurred during surgery. All patients reported complete resolution of lateral knee pain and a full return to preoperative activity levels. Iliotibial Z-plasty was successful for refractory iliotibial band friction syndrome. This improvement was maintained out to 8 years after surgery.