During Spain’s transition to democracy, the Basque nationalists resumed spreading the old theory that their people’s stock had a biological specific profile. Non-nationalist Basque intellectuals reacted by reminding that the myth of the Basque racial identity was tightly related to the Spanish Medieval hatred against the Jews and the Moors. The lecture will present the vain quest for a Spanish ethnic identity, since the Renaissance to Modern times, by considering its relationship with both the segregation of the religious minorities and the fetishizing of the Basque purity.