Pressure ulcer prevention needs nurses' awareness of sore classification/onset, its item characteristics, and its prevention. Using Pieper's Pressure Ulcer Knowledge Test, 126 critical care nurses' knowledge about pressure ulcer was examined. The questionnaire was divided into three categories including: (1) sore classification/onset; (2) wound characteristics, and (3) preventive measure. The level of nurse's knowledge was insufficient. The highest rate of correct answers belonged to section 2 - prevention of pressure ulcer. Programs aimed at raising nurses' knowledge accompanied by interventions intended to decrease incidence of pressure ulcer are important parts in educational programs. Continuing education may need to be added to the pressure ulcer care to improve the quality of care at intensive care units.