DescriptionAcute pain after cardiac surgery can progress to persistent pain if not managed effectively, which can negatively affect full recovery. This study examined the effectiveness of a nonpharmacological therapy, guided imagery, in reducing acute pain among postoperative open-heart patients in the cardiothoracic intensive care unit. The study also examined the effect of the guided imagery in anxiety, sleep, and vital signs of the participants. A quasi-experimental design was employed in this study. The participants (n= 24) from a regional hospital in New Jersey who had open heart surgery were recruited from January to July 2018. By using convenience sampling, they were assigned to interventional (n= 15) and control (n= 9) group. The interventional group received the guided imagery therapy in addition to the usual pain management in the unit, while the control group received the usual pain management only. Their pain and anxiety levels were obtained using the Numeric Rating Scale and State-Trait Anxiety Inventory questionnaires. The interventional group were also monitored for their vital signs and quality of sleep after receiving the therapy. The key findings include the significant decrease in pain and anxiety levels after the guided imagery therapy was offered on days 1, 2, 3, day of discharge, and one week after discharge (p < 0.05). The differences in vital signs and sleep were resulted not significant (p > 0.05). Patients reported that they used the guided imagery for pain, anxiety, and sleep. Based on the findings, guided imagery could be incorporated into the clinical practice in cardiothoracic intensive care unit to manage acute pain among open-heart surgical patients.