Purpose: This study was conducted to investigate ICU nurses' perceptions of communication difficulties, the importance of and satisfaction with communication with doctors, other nurses, patients, and family, as well as to explore communication barrier with patient families. Methods: Investigators developed a 15-item communication perception questionnaire and 58-item communication barrier questionnaire. Communication barrier included 4 domains: nurses, family, environment, and patient condition. A total of 151 ICU nurses with a minimum of one year of ICU experience participated. Results: ICU patients ($3.38{\pm}0.73$) were the most difficult group to communicate with, followed by family ($3.32{\pm}0.72$), senior nurses ($3.25{\pm}0.74$), doctors ($3.21{\pm}0.68$), and nurse colleagues ($2.64{\pm}0.73$). Doctors ($4.61{\pm}0.53$) were the most important group to communicate with, followed by nurse colleagues ($4.52{\pm}0.54$), patients ($4.49{\pm}0.58$), senior nurses ($4.44{\pm}0.55$), and family ($4.43{\pm}0.61$). Satisfaction with communication was the highest with colleague nurses ($3.60{\pm}0.68$), then senior nurses ($3.37{\pm}0.74$), family ($3.18{\pm}0.71$), patients ($3.09{\pm}0.75$), and doctors ($3.06{\pm}0.83$).The total score of the communication barrier was $2.83{\pm}0.52$, where each domain was scored as follows: patient condition $3.13{\pm}0.74$, nurses $2.83{\pm}0.60$, environment $2.81{\pm}0.66$, and family $2.76{\pm}0.57$. The ICU nurses reported that communication was difficult due to 'sudden deterioration in the patient's condition', 'being too busy', 'a noisy environment', and 'information not being shared between family members.' Significant differences were noted by age, clinical experience, and marital status of nurse respondents. Conclusion: The findings indicated that development of a protocol on communication between nurses and doctors as well as development of an educational program on communication skills are necessary.