In a group of patients with a preoperative diagnosis of ulcerative colitis, the stability of character traits and modes of mental functioning were studied after a major life event, major abdominal surgery, using the Karolinska Psychodynamic Profile (KAPP), an interview-based assessment instrument founded upon psychoanalytic theory. In addition, different personality and temperamental variables were assessed with 2 self-report instruments. The patients were assessed before surgery, and follow-up was made at least 1 year after their final scheduled surgery. Although the patients had undergone major abdominal surgery and convalescence between the assessments, the correlations between the scores before and after surgery were very high, and the levels of the scores were very similar. This was true for all the instruments, indicating that they assessed stable characteristics in the patients. The changes that did occur were mainly in the predicted direction. The results of this study suggest that the KAPP can assess modes of mental functioning and character traits that are relatively stable and only slowly variable.