BACKGROUND The incidence of invasive fungal infections (IFIs) in solid organ transplant (SOT) recipients has increased during the past 20 years and is associated with significant morbidity and mortality. In this post hoc analysis of a large, open-label, multicenter study, we evaluated efficacy and safety of posaconazole, a new extended-spectrum triazole, as salvage therapy for IFIs in SOT recipients. METHODS Twenty-three SOT recipients with proven or probable IFI and evidence of disease refractory to, or intolerant of, standard antifungal therapies received posaconazole oral suspension (40 mg/mL) 800 mg daily in divided doses. An independent, blinded data-review committee assessed patient diagnosis and outcome. RESULTS Complete or partial response was documented in 13 of 23 (57%) SOT recipients with proven or probable IFIs, including 1 of 2 (50%) refractory patients, 5 of 8 (63%) intolerant to prior therapy, and 7 of 13 (54%) who were both. Successes by type of IFI included 7 of 12 with invasive aspergillosis, 2 of 2 with invasive fusariosis, 1 of 1 with cryptococcosis, and 1 of 2 with zygomycosis. Treatment-related adverse events (TRAEs) were reported in 12 of 23 patients. Severe TRAEs occurred in 4 of 23 patients including increased levels of cyclosporine or tacrolimus requiring immunosuppressive dose adjustments in three patients and in one, termination of posaconazole. Severe TRAEs associated with renal and liver toxicities were uncommon. CONCLUSIONS Posaconazole was well tolerated and effective against IFIs including invasive aspergillosis, zygomycosis, fusariosis, and cryptococcosis in SOT recipients intolerant of or failing other antifungal therapies. Calcineurin inhibitor levels should be closely monitored in patients treated concomitantly with posaconazole to avoid toxicity from drug interaction.