These article analyses the description of the semantic class of adjectives presented in the first grammar of Quechua by Domingo de Santo Tomás. On the one hand, Santo Tomás’s representation is compared with the Iberian grammar tradition of the first half of the XVI century and with some contemporary linguistic theories in relation of its adequacy, on the other. It is demonstrated that Santo Tomás bases the major part of his description on the latin tradition. Nonetheless, the analysis reveals also some discrepancy with the tradition and convergence in some points with modern theories.