Letters are one of the most concise and effective forms of human communication. Together with the writer of the letter, the heart, mood, hopes, and dreams of the receiver are reflected in them. If personal letters between people are seen as a means of communication, then letters in literature and criticism are considered a separate genre, and studying the nature and different forms of their letters, which is the key to entering the laboratory of creators, is one of the urgent tasks. This article examines letters in literature and literary criticism and their place in the works of the great poets Alisher Navoi, A.S. Pushkin, Gafur Gulam and N. Gumilyov. It has been revealed that letters play an important role in studying the biography of creators entering the creative laboratory and are an important source of revealing their creative and spiritual image. Literary letters serve as a valuable resource for studying not only the lives and works of writers and critics, but also the period of writing, the history, the reasons for writing, and the mysteries with all their contradictions. Therefore, in the article, some letters of Uzbek and Russian writers are studied in a comparative-typological way.