This descriptive correlation study evaluated the pain intensity, pain distress and morphine consumption in patients recovering from coronary artery bypass grafting (CABG) surgery in an Australian intensive care unit (ICU) and compared patients' pain intensity ratings with ratings of the nursing staff. Forty-three patients and their attending nurses rated patients' pain intensity and pain distress levels at 8-hourly intervals throughout their stay in ICU. A maximum of five assessments was obtained in the first 48 post-operative hours from patients and their nurses. Pain intensity and pain distress were measured using separate 10-point numerical rating scales (NRS). Patients' worst pain intensity scores increased over time in ICU; the amount of opioids they received was small and decreased over time. Significant differences occurred between patients' and nurses' average pain intensity scores at each time point and, except for worst pain intensity measures at the first assessment, nurses consistently underestimated patients' pain. These results indicate that patients in ICU following CABG can experience considerable pain, which is not always relieved. The application of regular systematic pain assessment and improved communication, together with the administration of adequate pain relief are necessary if nurses are to manage patients' pain effectively.