Influenza infection can be severe in bone marrow transplant (BMT) recipients. Although yearly epidemics occur worldwide, and a higher risk of complication is expected in these patients, few studies have addressed the impact of the new neuraminidase inhibitors in the prognosis of influenza after BMT. Influenza A or B infections were found in 39 of the 66 patients (59%) showing a positive nasal wash by DFA. Influenza A was diagnosed in 18 patients and influenza B in 23 patients; two patients were infected by influenza A and B with 84- and 90-day intervals between episodes, respectively. Of the 41 episodes (61%) of influenza A or B, 25 infections occurred during the spring and summer months. Oseltamivir was introduced within 48 h of symptoms appearing. Only two patients (5.1%) developed influenza pneumonia, and no patient died of influenza. A total of 22 patients (56.4%) acquired influenza before day +180 when preventive vaccination strategies are precluded owing to poor immunogenicity of the vaccine during this period. Oseltamivir proved to be safe and appears to have played an important role in the outcome of influenza infection in this population. The therapeutic and/or prophylactic benefits of Oseltamivir in BMT recipients remain to be demonstrated in randomized, prospective trials.