The authors of 4 National Institutes of Health-sponsored antibiotic treatment trials of patients with persistent unexplained symptoms despite previous antibiotic treatment of Lyme disease determined that retreatment provides little if any benefit and carries significant risk. Two groups recently provided an independent reassessment of these trials and concluded that prolonged courses of antibiotics are likely to be helpful. We have carefully considered the points raised by these groups, along with our own critical review of the treatment trials. On the basis of this analysis, the conclusion that there is a meaningful clinical benefit to be gained from retreatment of such patients with parenteral antibiotic therapy cannot be justified.