The hand of health care workers is the main route of cross-transmission of the nosocomial infections so, hand hygiene is the main procedure in the transmission reduction of nosocomial pathogens. The aims of this study were the following: assess the quantitative and qualitative contamination in hands of health care workers in different hospital units, compare the effectiveness of hand hygiene with water and soap versus alcohol-gel and the changes in bacterial flora on hands damaged by use of gloves and/or handwashing. The samples were obtained from the dominant hand of health care workers in intensive care unit (UCI), medicai and surgical wards and Office workers, and put into sterile polyethylene bag, before and after hand hygiene with alcohol gel or water and soap, with and without standardized protocols. Additionally, 15 volunteers with skin damage resulting from the use of gloves and/or handwashing were included, and 15 Office workers and students, submitted to repeated handwashing with water and soap. The contamination on hands of volunteers in criticai unit was about two times bigger than in the other units, as well as Staphylococcus aureus (10%) and Gram-negative bacillus (50%) multirresistant. The average reduction in the number of organisms before and after hand hygiene of any procedures showed statistically significant differences, with similar results when alcohol gel (FR = 0,07-0,40) and water and soap (FR = 0,25-0,36) were compared, with just two exceptions, in the eight comparisons. Although a flora of the damaged hands did not differ qualitative and quantitative from the healthy ones, only the latter showed a significant reduction in the contamination (FR = 0,32-0,85), in the procedures investigated. The efficiency of hand hygiene with alcohol gel was similar to handwashing with water and soap and the last one less irritating, fact that could increase compliance in hand hygiene to health care workers. ; Dissertação (Mestrado) ; A mão do profissional de saúde é a principal via de transmissão cruzada ...