Overall, consumption of omega-3 fatty acids from fish or from supplements of fish oil reduces all cause mortality and various CVD outcomes. The evidence for ALA supplements is sparse and inconclusive. The adverse events due to consumption of fish oil or ALA supplements appear to be minor. Many questions remain. The studies were heterogeneous with regard to the methods of estimating fish or omega-3 fatty acid intake, background diets, settings, and the methods of reporting results. Due to these reasons, the validity of applying the results of studies conducted in countries outside of the US to the US population is uncertain. The optimal quantity and type of omega-3 fatty acid, and the optimal ratio of omega-3 to omega-6 fatty acid (if such an optimal ratio exists), remain undefined. Not much data exists concerning the needs of different subpopulations. Different types of fish and the method of food preparation may have different effects. Future research needs to address these issues.