Gueiler was born in Cochabamba, to Moisés Gueiler Grunewelt, an immigrant from Germany and a Bolivian mother, Raquel Tejada Albornoz. She received a BA degree from Instituto Americano in Cochabamba. In the 1940s, she joined the Movimiento Nacionalista Revolucionario (MNR). When that party came to power as a result of the 1952 National Revolution, Gueiler became a member of the Congress of Bolivia, serving in that capacity from 1956 until 1964. In 1964, she went into exile abroad after the MNR was toppled from power by generals Barrientos and Ovando. She spent the next fifteen years out of the country, and joined Juan Lechín's Revolutionary Party of the Nationalist Left (PRIN).