Nineteen patients received single-dose exposure to 600 rad delivered within 48 hours of total hip arthroplasty (THA) with shielding of the prosthesis region for the prevention of heterotopic ossification. The patients were considered at high risk for developing heterotopic ossification (HO) because of hypertropic osteoarthritis, post-traumatic osteoarthritis or the presence of previously-formed ectopic bone. The average follow-up period was 42 months (range, 37 months-48 months). At a follow-up study, all hips except one were classified as Brooker class 0. The single exception was classified as class I. All patients were asymptomatic at the last follow-up study and no component demonstrated subsidence or radiolucent line indicative of loosening. The authors concluded that 600 rad, single-fraction radiation therapy is cost effective, convenient and safe for the prevention of heterotopic ossification after total hip arthroplasty.