Ecological, evolutionary and economic issues involved in introducing genetically modified organisms (GMOs), mainly in agriculture, are discussed. The ecological and evolutionary impacts identified hamper (economic) valuation of GMOs and their biosafety regulation and creates difficulties for planning for sustainable development. Assessment of the desirability of releasing GMOs is difficult because of lack of communal agreement about the risks involved, about how much precaution should be exercised given collective risks, and disagreement on the appropriate social criterion to apply. Changes in legal liability are not always economic and cannot eliminate the social conflict generated by GMOs. The economics of developing and marketing GMOs is explored, assuming the type of intellectual property rights in GMOs in the United States. It is found that the economics of developing and marketing GMOs favours large enterprises as primary suppliers. In marketing GMOs, sales to larger-sized commercial farms rather than smaller-sized ones are preferred. GMOs preferred for development are those designed to satisfy large agricultural markets, mostly located in higher income countries. The patenting of GMOs, co-evolution, various social conflicts in the use of GMOs and legal liability for damages caused by GMOs are discussed both from a socioeconomic and biosafety point of view.