||Background As maintenance of lifestyle change and risk factor modification following completion of cardiac rehabilitation (CR) has been shown to be notoriously difficult, we developed a brief self-regulation lifestyle program for post-CR patients. Design Randomized-controlled trial. Method Following completion of CR 210 patients were randomized to receive either a lifestyle maintenance program (n=112) or standard care (n=98). The program was based on self-regulation principles and consisted of a motivational interview, 7 group sessions and home assignments. Risk factors and health behaviors were assessed at baseline (end of CR), and 6 and 15 months thereafter. Results ANCOVAs showed a significant effect of the lifestyle program after 6 months on blood pressure, waist circumference and exercise behavior, only the latter of which remained significant at follow-up (15 months). Mediation analysis demonstrated that the treatment effect on exercise behavior could be explained by an effect on self-regulation skills. Furthermore, the lifestyle intervention program was associated with a 12% reduction in self-reported cardiac hospital admission rates. In addition, patients in the intervention group had significantly fewer uncontrolled risk factors as compared to the control group. However, there was only a long-term beneficial intervention effect on obesity and physical inactivity, but not on other individual risk factors (increased waist circumference, raised blood pressure, raised TC/HDLC-ratio and smoking). Conclusion This trial indicates that a relatively brief, theory-based lifestyle program is capable of inciting and maintaining improvements in exercise adherence. It is suggested that patients may need ongoing attention and guidance, for example in the form of (internet-based) booster sessions, as long-term consolidation of changes is arduous.