Purpose: The purpose of this study was to evaluate knowledge, attitude, and compliance regarding hand hygiene according to the profession of ICU health care providers. Method: Data were collected by questionnaires and by recording of direct observations of 143 health care providers in 4 intensive care units. With SPSS/WIN 12.0 t-test, ANOVA, and ${chi}^2-test$ were used to analyze the data. Results: The level of knowledge regarding handwashing among the nurses was higher and a more positive attitude was shown compared to physicians. Overall handwashing compliance was low among all ICU health care providers, but nurses had better compliance than any other health care providers and significantly higher frequency for handwashing before care and after care activities. All of professions had lower scores on the appropriate length of time for handwashing and areas that need to be scrubbed. The level for nurses was medium and for physicians, the lowest of all professions. The appropriate agent for handwashing and the method of drying for handwashing compliance was high in all professions. Conclusion: The results suggest that multidisciplinary interventions are needed to develop an environment for appropriate handwashing as well as to reinforce importance of handwashing compliance for health care providers.