OBJECTIVE: The aims of this study were to investigate the time-course of depressive mood in patients with coronary artery disease during a secondary prevention rehabilitation program, and to analyse how different pre-treatment levels of depressive mood during a treatment phase were related to the degree of lifestyle change at 36 months follow-up. SUBJECTS: The study group comprised 109 of the original 183 consecutive coronary artery disease patients (91 male and 18 female) of whom 48 recently had experienced an acute myocardial infarction, 36 had been treated with coronary bypass surgery, 13 with percutaneous transluminal coronary angioplasty, and 12 had angina pectoris that had not been invasively treated. The subjects were divided into 3 subgroups based on their pre-treatment level of depressive mood. METHODS: Depressive mood was assessed at baseline, after 4 weeks and 12 months, using the depression subscale of the Hospital Anxiety and Depression scale. Lifestyle changes analysed included diet, smoking, relaxation (stress management) and exercise. RESULTS: Overall depressive mood ratings were significantly lower, both at the 4-week and 12-month assessments, compared with baseline, with the greatest improvements in patients with higher Hospital Anxiety and Depression measured depression. Original levels of depressive mood were not found to influence change of lifestyle habits during a 36-month follow-up period. CONCLUSION: Depressive mood might not be an obstacle to lifestyle changes when participating in a behaviourally oriented rehabilitation program including exercise-training, which might be a component important for improved depressive mood.