Opportunistic fungal infection is a rare but severe complication in allogeneic bone marrow transplant (BMT) recipients. We report a 49-year-old patient who developed pneumonitis after BMT, due to a Mucorales fungus (class Zygomycetes), Absidia corymbifera. Infections due to mucormycosis are likely to become increasingly recognized even though the occurrence after BMT has only been described sporadically. We postulate that the patient was contaminated before BMT despite no intensive drug treatment or other iatrogenic features, related to his poor living conditions and developed the infection during aplasia. He immediately received i.v. liposomal amphotericin B (AmBisome) and GM-CSF. Because there was no response, the infected area and necrotic tissue were resected. Despite initial clinical and biological improvement and the absence of Mucor on mycological examination post-surgery, the patient died 3 weeks later from bilateral pulmonary infection and multiorgan failure.