We executed a blanket-use program of intranasal application of mupirocin ointment to control the propagation of methicillin-resistant Staphylococcus aureus (MRSA) that occurred in a thoracic surgery ward of a university hospital. During an intervention of 14 weeks, all patients admitted to the ward for scheduled surgery received the ointment to their nares three times daily for 3 days before surgery, once on return to the ward, and three times weekly for the following 2 weeks. None of 84 patients was newly colonized with MRSA, and the daily rates of patients with MRSA in a recovery room in the ward significantly decreased in the period. We consider that the unselective application of mupirocin ointment is one of the effective measures to control MRSA propagation in a thoracic surgery unit.