We retrospectively reviewed the charts of 154 patients of various subgroups treated with the free vascularized fibular graft procedure for osteonecrosis of the femoral head (ONFH), evaluating pre- and postoperative Harris hip scores, hip range of motion, radiographs, and number of conversions to total hip arthroplasty (THA). Patients were followed a minimum of 1 year (mean, 6.8 years, range, 1 to 19 years). Athletes and patients with pyarthrosis-related osteonecrosis had high Harris hip scores at final review with scores of 94 and 97, respectively. Patients with ONFH after a slipped capital femoral epiphysis or following pregnancy had a low conversion rate to THA at 6% and 8%, respectively. Twenty-five percent of patients with transplant-related osteonecrosis of the femoral head were converted to THA at an average of 2.7 years. However, with select subsets of patients (athletes, pregnancy, organ transplant, femoral neck non-union, slipped capital femoral epiphysis, infection) the FVFG can result in a high rate of success.