This review provides an overview of the use of omega-3 concentrates [both prescription omega-3 fatty acid concentrates (P-OM3) and OTC fish oil] to lower triglycerides in people who have moderate hypertriglyceridaemia (triglycerides in the range of 150–500 mg/dl). The objectives were to examine clinical evidence, describe the magnitude of effects and predict future clinical use of P-OM3. Published, peer-reviewed studies of omega-3 concentrates were included if they were placebo-controlled, double-blind, of sufficient size to demonstrate triglyceride lowering, and studied a population described as having a mean baseline triglyceride value of 150–500 mg/dl. Studies using the 4-g dose of P-OM3 were used to develop a model of percent triglyceride lowering as a function of baseline levels. P-OM3 are effective in reducing triglycerides by approximately 30% in this population and are likely to be combined with other drugs (e.g. statins) to treat combined dyslipidaemia.