The contamination of fish with methylmercury (MeHg) could hamper the health promoting properties of fish. Currently, there is strong evidence about the health benefits of seafood consumption. When consumed by the mother before and during pregnancy it improves neurodevelopment of infants and toddlers. Thereafter it reduces the risk of cardiovascular and other chronic diseases. The benefits of fish are mainly due to its content of omega-3 long chain polyunsaturated fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Other constituents, such as high biological value proteins, fat-soluble vitamins, minerals and trace elements contribute to the benefits. On the other hand, there is also convincing evidence about the adverse effects of MeHg on neurodevelopment both during gestation and in early childhood. We herein review the effects of mercury on health. Based on international evidence and new data on the mercury content in Chilean fish, we also propose a recommendation for fish consumption for our population.