Mupirocin is an antibiotic for topical application developed by SmithKline Beecham in the United Kingdom. To study the effects of mupirocin nasal ointment for eliminating nasal carriage of MRSA and preventing recolonization, and its effect on normal flora of the anterior nares, 60 mg of mupirocin nasal ointment was applied to both sides of the anterior nares (30 mg each) three times a day (morning, evening and at bedtime) for three days. Seven hospital staff who were found to have nasal carriage of MRSA at pre-study screening and who gave consent to participate in this investigation in writing were enrolled. Two cases were excluded because they were negative for MRSA just before the first application. By the day after the last application, nasal carriage of MRSA was eliminated in all the 5 cases (100%) assessed for the elimination effect, and one week after the last application. MRSA was not detected in any of these cases except one from which a specimenwas not collected. There was no problem in safety in any of the subjects. Recolonization with MRSA was not observed for 4 weeks from the last application. Mupirocin nasal ointment did not affect greatly the flora of the anterior nares. In conclusion, mupirocin nasal ointment is a safe drug which can eliminate nasal carriage of MRSA and prevent recolonization with MRSA without destroying the flora of the anterior nares.