The article deals with structural-semantic study of the medieval "The Story of Tristam and Iseult". The novel represents interest for analysis as it occupies intermediate position between based and a legends novel and a fairy tale and demonstrates development of the literary genre of novel from myth through fairy tale t it fiction. The novel is connected with the myth on the level of mythological archetypes and may be related to initiation group of myths, demonstrating development and transformation of the central character. The novel is connected with the fairy tale at the level of characters' functions that constitute the pilot lines.

The inner meaning of the myth acquires archetypal value in fiction and reflects disconnection of everyday life rituals by myths.