Sesotho is one of the African Languages where sentence negation is expressed by means of bound negative morphemes. It has only three negative morphemes which arespread across the Sesotho matrix and subordinate clauses. They are the negative morphemes /ha/, /sa/ and /se/.These morphemes are bound verbal morphemes that negate various predicate forms and only appear in restricted sentence types. The central aim of this paper is to examine sentence constructions that realize negation by means of the negative morpheme /sa/ and its syntactic distribution within copulative verbs, non - copulative verbs, deficient verbs and aspect morphemes over a full range of inflectional categories such as tense, aspect and mood. This morpheme will be examined within the general framework of the Minimalist Programme, which holds that inflectional categories occur as heads of phrasal categories. This paper will further illustrate the morphological representations of these morphemes within Beard’s (1995) Lexeme-Morpheme Base Morphology, which defines morphology as the sum of all the phonological means of expressing the relations of constituents in words, of words in phrases and of phrasal constituents in sentences. It distinguishes lexemes from bound morphemes.