Spanish politician and doctor. He was born in Vigo (Pontevedra) on 27 October 1926. He studied medicine at the University of Cádiz and Seville, graduating with an Extraordinary Prize and doctoring as a specialist in lung and heart. He was Clinical Chief at the University Hospital of La Paz. Moreover, Fuejo Lago participated in the first heart transplant that was carried out in Spain, forming part of a prestigious team together with Cristóbal Martínez Bordiú and Vital Aza. He had his first contacts with political activity during the fifties, when he met Enrique Tierno Galván and joined the Partido Socialista Popular (PSP/Popular Socialist Party). He was also one of the founders of the Junta Democrática (Democratic Board). In the first democratic elections, held in 1977, he was one of the three deputies elected for the electoral district of Madrid in the PSP-Unidad Socialista candidacy, along with Tierno Galván and Raúl Morodo. Member of the Mixed Group of the Congress, he was very active in the meetings and negotiations for the elaboration of the Spanish Constitution of 1978. After the merger between the PSP and the PSOE, he was elected deputy, now for PSOE and for the district of Madrid in the I and II parliamentary terms. He was a member of the PSOE Federal Executive. He was appointed Vice President of the World Health Organization (WHO), a position he resigned shortly after. He also held the chairmanship of the Comisión del Defensor del Pueblo (Ombudsman Committee) in the Congress of Deputies and he was elected member of the Consejo de Seguridad Nuclear (Nuclear Safety Council), where he became its president from 1987 to 1994.