Pain after Cardiac Surgery (CS) is the most common patient complaint. However the first 48 h after surgery, when patients' pain is the most severe, is generally spent in the Intensive Care Unit (ICU). It is almost impossible for patients to report their pain because of their inadequate level of consciousness in the ICU. Many factors alter verbal communication with patients, such as administration of sedative medications, mechanical ventilation, and patients' changed level of consciousness. This descriptive study was conducted for the purpose of describing the experience of pain in CS patients in the ICU and determining situations that affect their pain. This research was conducted with 300 adult patients at a Ministry of Health Hospital who stayed in a cardiac surgery ICU post-operatively for a minimum of 48 h, had a sternal incision, chest tube, and required mechanical ventilation. The data were collected from the patients in face-to-face interviews by the researchers following transfer from the ICU to the surgical ward within 48 h of transfer. Most patients described their pain as aching (n = 177) and throbbing (n = 154). The presence of chest tubes (n = 95), endotracheal tube suctioning (n = 47), change of dressings (n = 27) and the use of air mattresses (n = 20) were also identified as painful experiences for patients. Based on these results it can be said that CS patients experience pain in the ICU, however they verbalized it with different words and identified different situations that decreased or increased their pain, which shows the subjective and complex nature of pain.