The paper deals with the problem of varying the idiostyle of a public language personality in media discourse, which is important for the research on the character of interaction between a personality and a media sphere. On the basis of M. A. Zhakharov’s media discourse in the programs «Dithiramb» and «Analysis of the flight» on the radio «Echo of Moscow», the author of the paper analyzes the constant and variable signs of the idiostyle, linguistic and extralinguistic
ones, and reveals objective and subjective factors, determining the peculiarities of the language personality’s speech behaviour in media communication. Classified as constant signs of the idiosty are gender peculiarities, psychological (defined by temperament, character), social (status
dependent), professional as well as cultural and speech peculiarities characteristic of man. Set off from other variable signs of idiostyle are its situational manifestations in different formats of communication, thematic variation, influence of addressee factor, genre transformations. The objects of special examination in the paper are author’s individual emonstrations of a personality in media discourse depending on the format of communication, situations and addressee factor.