Ernesto Guevara de la Serna was born in Rosario, Argentina, on June 14th, 1928. His parents were Ernesto Guevara Lynch, a civil engineer of Irish descent, and Celia de la Serna, of Spanish descent. It was a middle-class family with strong left-wing tendencies. The Guevaras were free-thinkers, admirers of José Martí, and supporters of the Republican cause during the Spanish Civil War.

At the age of two, Ernesto is diagnosed as suffering from asthma, and the family moves to Córdoba for health reasons. There, his father tries to cure his son by introducing him to all manner of sports. Friends of that period remember Ernesto as being energetic, highly individualistic, sloppy in dress, sober in his likes and needs, timid, shy, and possessing a mania for reading and learning. But what most fascinates the youthful Ernesto is the great outdoors, and by his seventeenth year he has criscrossed Northern Argentina on a bicycle outfitted with a small motor.

Plagued continually by asthma, Ernesto enters the University of Buenos Aires and begins his medical studies, but takes to the road whenever the opportunity presents itself. In late December, 1951, he sets off with his friend, Alberto Granados, for a long trip across Latin America by motorcycle. The trip will last ten months, but the motocycle gives out when they arrive in Chile. The two young men reach Peru on foot and spend some time in a leprosarium, working in the laboratory and living with the lepers. When the time comes to leave, the pair cross the Amazon on a raft and reach Leticia, Colombia. Che goes on to Venezuela, where Alberto Granados chooses to stay behind and work, and then on to Miami. Ernesto finally returns to Buenos Aires in August and promptly resumes his studies, graduating in March of 1953.

Graduating as an allergist, Ernesto decides to go to Venezuela to work with his friend Granados. En route, in Bolivia, he meets a fellow Argentine that will forever alter the course of his life, Ricardo Rojo, an exiled, antiperonist lawyer. Accompanied by Rojo, he resumes his journey, but is convinced to go to Guatemala instead of Venezuela ("But Guevara, why do you want to go to Venezuela, a country that's only good for making money? Come with me to Guatemala where there's a real social revolution taking place. That's something that you should see, old man!").