The present work is a study of metafictional aspects in three novels of Miguel de Unamuno. The first chapter provides a definition of metafiction and positions the idea of metafiction within the Spanish novel. This fictional concept is traced through the history of the Spanish novel beginning with its first appearance through its manifestation within the novels of Unamuno. In the second chapter, Unamuno's narrative style is described. The focus is placed on the author's own theory of the novel and on the metafictional elements of his style which illustrate him as an innovative novelist. A relevant way to understand the metafictional aspects in Unamuno's narrative is to analyze the fictional techniques that reflect the idea of metafiction in Niebla, Como se hace una novela, and San Manuel Bueno, martir. The function of the techniques is discussed in order to understand the innovations which Unamuno presents in these novels.