Purpose: This study was done to determine the rate for handwashing by intensive care unit nurses according to the content of nursing tasks, to investigate the relationship between hand washing practice evaluated by nurses themselves and their actual practice observed, and finality to provide basic materials for strategy for hand washing education. Method: Data were collected by observing 27 nurses working in intensive care units of a hospital in Uijeongbu, Gyeonggi-do and by using observation and a structured self-assessment tool. Collected data were analyzed with SPSS and SAS. Results: The handwashing rate for the nurses was 4.3%. The handwashing rate was high in proportion to the risk of cross infection. In addition, the handwashing rate was highest in nurses working in the neurosurgery intensive care unit. The average score for self-assessment of handwashing was $49.42{pm}3.78$ points and it was higher than their actual practice of handwashing. Conclusion: In order to improve handwashing by nurses, it is necessary to educate them on the importance of handwashing. In addition, there should be strategies for standardizing knowledge and attitudes to handwashing and inducing nurse:3 to practice hand washing in compliance with the policies and working conditions of the institution.