A recent outbreak of methicillin-resistant Staphylococcus aureus (MRSA) infection in neonatal intensive care unit (NICU) in a teaching hospital was investigated. A total of 25 MRSA isolates, 16 from the patients and nine from the staffs (carriers), was collected for the study. The possible relationship among the isolates was investigated by using antibiograms and restriction enzyme analysis of plasmid DNA. Control strategy of the MRSA nosocomial infection was proposed after the study of antibiograms and plasmid profile. There were four plasmid patterns (I-IV), each containing 7, 8, 2, and 8 isolates. Six of the 16 isolates from the patients had identical plasmid patterns as the carriers (I and II). Person to person transfer via hand contact by medical personnel was found to be the most frequent mode of transmission identified in the outbreak of MRSA nosocomial infection in the NICU. Our strategy for control of the outbreak and elimination of the MRSA from all patients and carriers was successful after intensive surveillance and control measures. These included (a) strict isolation and cohorting; (b) hand washing between patient contacts to prevent transmission; (c) treatment of the carrier state in health care workers and patients with safe and effective topical agents such as mupirocin.