Background: Cardiovascular disease (CVD) is a major contributor of mortality and loss of disability-adjusted life years in Norway. World Health Organization and Norwegian authorities acknowledge the importance of prevention in CVD in terms of reducing modifiable risk. Several strategies have been proposed for achieving the goal of reducing these risk factors. However, there seems to lack economic evaluation of primary prevention of CVD by a lifestyle change in a Norwegian context. Objective: To assess the cost-effectiveness of primary prevention by a lifestyle change in terms of exercise and diet on CVD compared do-nothing in Norway. Methods: A state transition Markov model was developed to assess changes in costs and quality-adjusted life years by primary prevention of CVD in a cost-utility analysis. Effect from a lifestyle change was modeled through a reduction in blood pressure and cholesterol. Three perspectives were applied to reflect different costs; 1) healthcare, 2) extended healthcare, and 3) societal perspective. Results were stratified for different groups of age and risk to reflect heterogeneity. Uncertainty and value of information analyses were performed to assess uncertainty and whether there was value in acquiring additional evidence on key parameters in the model. Results: Over a lifetime horizon, incremental cost-effectiveness ratios of the intervention according to perspectives described above were; 1) NOK 32,879 per QALY gain, 2) NOK 4,676,514 per QALY gain, and 3) NOK 4,409,942 per QALY gain. In a healthcare perspective, lifestyle intervention had a probability to be cost-effective of 86.5% for relevant WTP threshold. While extended healthcare and societal perspectives had a probability of 0.0% and 9.6% respectively. Population expected value of perfect information (EVPI) demonstrated that there was great value of acquiring new evidence, with an estimate of approximately NOK 11.1 billion. Furthermore, evidence on effectiveness of lifestyle intervention has the highest partial EVPI of approximately NOK 10 billion. Conclusion: Recommendations on cost-effectiveness were dependent on perspective of analysis. Lifestyle intervention was likely to be cost-effective in a healthcare perspective; however, there might be value of acquiring new evidence before making a decision on costeffectiveness. Lifestyle change was not cost-effective in an extended healthcare perspective recommended by health authorities. Results of this thesis imply that the field of disease prevention on CVD risk and health behavior requires further research and awareness.