Posaconazole or Fluconazole for Prophylaxis in Severe Graft-versus-Host Disease (Original Article, N Engl J Med 2007:356;335-347). The second sentence of the third paragraph under Efficacy (page 341) should have read “In other analyses, posaconazole was superior to fluconazole in reducing the incidence of proven or probable aspergillosis (odds ratio, 0.31; 95% CI, 0.13 to 0.75; P=0.006) during the treatment period and was superior to fluconazole in reducing the incidence of breakthrough proven or probable invasive fungal infections (odds ratio, 0.30; 95% CI, 0.12 to 0.71; P=0.004) and invasive aspergillosis during the exposure period (odds ratio, 0.17; 95% CI, 0.05 to 0.57; P=0.001)” rather than “invasive aspergillosis during the treatment period.” The text has been corrected on the Journal's Web site at www.nejm.org.