Methicillin-Resistant Staphylococcus aureus (MRSA) strains with the exception of urinary strains were isolated from the inpatients in urology ward hospitalized in 2003 and medical workers. Biotype according to the production of coagulase, enterotoxin and mupirocin sensitivity, and genotype by pulsed field gel electrophoresis (PFGE), and clinical background were determined for the MRSA strains to analyze the transmission route of the infection. In 34 medical workers in urology ward, MRSA were isolated in 6 (17.6%) workers from the nasal cavity, and the rate of colonization in doctors was higher than in nurses. Furthermore, mupirocin-resistant strains were isolated from two medical workers. 18 MRSA strains were isolated in 2003 and the accounting was 8 strains from wounds, 6 strains from sputum or nasal cavity, 3 strains from blood, and 2 strains from urinary tract. Most of the patients with MRSA had operations under general anesthesia or were under severe conditions with malignant tumors. No MRSA was detected at the same time from the same rooms. There were some rooms in which the MRSA detected rate was high, however no MRSA was isolated from hospital environments and dumping bacteria. These results suggest that the involvement of the medical workers and the spread of MRSA in the society might be important as infection source and for transmission of MRSA in hospital.