The goal of this paper is to make a suggestion to include Spanish conjunction variants e and u in the basic vocabulary list of National Curriculum. RAE-ASALE(2010) describes that the simple coordinate conjunctions can be copulative (y, its variant e, ni), disjunctive (o, its variant u, ni) and adversative (pero, sino, mas). However, all these conjunctions, without exception, are listed as independent lexical items in RAE(2014), where the variants normally are exposed as the sub-content of lexical entries according to the norm. This indicates that if the basic vocabulary list of National Curriculum play a role of the lexical set, it must include both types of conjunctions: unmarked form ( y, o) and marked form (i.e.: e, u, ni). Nevertheless, the actual National Curriculum(2015) does not include the two variants e and u in its basic vocabulary list. We insist that National Curriculum must apply an uniform criterion to the lexical registration and the teaching and learning of Spanish conjunction variants should be carried out based on the morpho-phonetic properties of words and the particular syntactic-pragmatic uses in various contexts.