This article contributes to debates about fascist influences among Argentina's guerrilla groups of the 1970s. From the overall perspective of developments in Argentine nationalism, it traces back the history of the far-right Alianza Libertadora Nacionalista and Tacuara and assesses their significance as the nuclei from which later guerrillas came. Based on police reports and periodical publications from the period in question (c.1937 – c.1973), it makes some generalisations about the collective biographies of militants. While not contradicting the widely held view that originally fascist groupings played a role in the emergence of Argentine guerrillas, the article introduces some nuances into this argument. Particular emphasis is given to the role of Peronism and the Cuban Revolution as facilitators of changes in Argentine nationalism.