Bacterial cultures of the transfer forceps, 4"$ imes$4"mesh gauze and polluted air of nursing units of general surgery, internal medicine, gynecology and pediatrics of S.N.U.H. were carried on for S consecutive days (from 17th to 21s1 August, 1972) to investigate the degree of contamination of such instruments which were used in dressing the patients. 1. The average hospitalized patients for each nursing unit were 24 persons. 2. The frequency of dressing, and using forceps and gauze in surgical nursing unit were 25,316 and 66 times respectively. Actually the forceps were used most frequently. There was no dressing in the nursing unit of internal median. 3. Most of dressing were carried on from 11 : 00 to 13 : 59 o′clock. 4. Averagely 121.5 persons passed through each nursing unit. 549 visitors dropped in the nursing unit of gynecology in maximum, and 219 visitors in the nursing of internal medicine in minimum. The visitors rushed in from 11 : 00 to 13 : 59 o′clock to he 142.5 persons for each nursing unit in average. 5. Colony counts after the bacterial cultures of the forceps and gauze disclosed 1098.44 and 704.51 per plate respectively. 6. The degree of contamination was parallel to the duration and frequency of dressings. 7. The degree of contamination of the instruments was severest in the nursing unit of internal medicine, and !east in the nursing unit of gynecology. On the matter of gauze, the contamination was most extreme in the pediatric nursing unit. 8. There was no significant daily differences in terms of contamination throughout the week. 9. It was disclosed that empty forceps jars were less contaminated than the jars with solution of any kind. 10. Bacterial cultures of the polluted air in corridor showed 73,88 colony counts per plate.