This article is devoted to the peculiarities of the lexicalisation of concept INSANITY in literary texts based on the material of contemporary novels by American and British writers. The purpose of the study is the analysis and classification of lexical means that form the portrait of a mentally ill person in the studied works. The object of the analysis is the lexemes-verbalisers of the concept INSANITY, the language means of creating a mentally ill character in literary texts form the subject of our work. The concept in this study is understood as a discrete mental entity, a basic unit of a person’s mental code. It has an ordered structure, which is the result of cognitive activity of the individual and society, and which carries complex information about the reflected subject or phenomenon. Using the continuous sampling method, we selected text fragments containing portrait descriptions of characters suffering from mental disorders. It has been hypothesised that conceptual features DESTRUCTION, DEFORMATION, AFFECTIVENESS, which are nuclear features of concept INSANITY, are lexicalised in the texts under study when the authors create the portrait of the mentally ill character. Our research also found that the opposition of FRIEND-FOE is one of the most important mechanisms involved in the conceptualisation of the phenomenon of insanity, which is indicated by the frequent lexicalisation of conceptual feature FOE in literary texts. After analysing the lexical means involved in creating the portrait of the literary character with mental disabilities, we identified a set of prototypical characteristics of the appearance of a mentally ill person. Based on the material of the works, we studied narrative compositional form “description” pertaining to the portrait of the mentally ill character. The characteristics obtained were grouped into the following thematic groups: text fragments describing voice / speech, body, eyes, face, overall appearance, body plastics, poses, and smell. All such contexts offer the reader quanta of information, functioning as markers of a person’s mental illness.