Optimal management of infected total hip arthroplasty poses a major challenge to clinicians. Exchange arthroplasty is usually advocated but has high rates of surgical morbidity and is expensive. Debridement with prosthesis retention is associated with less morbidity, but high rates of relapsed infection have been described. To estimate the effectiveness and cost-effectiveness of these 2 strategies among older patients, we used a Markov model to simulate patients' projected lifetime clinical course in hypothetical cohorts of 65-year-old and frail 80-year-old men and women. Initial debridement and retention increased life expectancy 2.2-2.6 quality-adjusted life months and had a favorable cost-effectiveness ratio in all cohorts. Results were most sensitive to the annual rate of relapse after debridement and age at initial diagnosis of infection. In the absence of prospective clinical trials, debridement and retention is a reasonable strategy for treatment of older persons with staphylococcal or streptococcal infection and a nonloosened prosthesis.