This article proposes a theoretical discussion on the relationship between translation and ontology. The so-called ontological turn in cultural anthropology has not only questioned the modern naturalistic ontology, which until now had been imposed as universal, but also the use of the notion of culture and cultural translation. The ontological question, however, has received little attention in analytical terms in Translation Studies from an interdisciplinary approach, especially regarding postcolonial contexts. For this reason, after illustrating the debate on the notions of culture and cultural translation in Translation Studies, this article proposes the concept of ontological translation as an indispensable theoretical device to investigate those translation processes characterized by differences that can be defined as ontological and not only cultural. In order to analyze the hermeneutic potentialities of ontological translation in Translation Studies, the case study proposed is that of the bilingual Quechua-Spanish author José María Arguedas (1911-1969) who, as an anthropologist, author and (self-)translator, reflected on the complexity of translating the Quechua worldview into Spanish.