This article discusses the process for obtaining genuine informed consent for the participation of human subjects in research in developing countries. We discuss the consent process in the light of recently published guidelines, the experience of nutrition and health research projects, and the ethics review process of the Instituto de Investigacion Nutricional with peri-urban and rural populations in Peru. We discuss the cultural context in relation to (i) who should be involved in the decision for participation, especially for research in children and in community settings; (ii) when to use written or verbal consent; (iii) the format and presentation of the consent form to ensure understanding by the target population; and (iv) the process of how and by whom information is given and consent is obtained. Common concerns of participants with regard to their involvement in research studies are presented, as well as aspects that participants find difficult to understand. Some specific concerns of conducting research with Indigenous Peoples are discussed. We recommend future research to further understand and implement informed consent processes to assure genuine and voluntary consent in different developing country contexts.