This paper examines the lexical competence of interpretes in regards to its structure (declarative competence) and usage (procedural competence) tp study the points at which the interpreters' lexical system differs fromthat of average noninterpreters. Recnt theoretical and empirical studies on cognition and neuropsychology are referenced to xplainor support the hypothetical characteristics of interpreters' lexical competence, which inclde the densification of lexical nework, the balance of L1-L2 system, the strengthened connection of paradigmatic (rather than syntagmatic) words, the automaticity of lexical transition, as well as the long-tem retenton of lexis acquired during interpretng sessions. These presentations of hypthetical theories are further strengthened by the discussion on the scientific methods that should verify the presented theories. Due to the lack of technical possibilities to examine neurona activities on the fine level of respective nurons with its structure and function, this discussion emphasized the psychological perspectives.