This thesis is an investigation on the influences that the Spanish Guitar and the traditional music from Spain had on the impressionistic composers of the late 19th century and early 20th century. I have also inquired on the opposite influence, the impressionistic influence on Spanish composers.It contains a description of the characteristics of the two musical genres, informations on their most renowned composers’ composing style and an analysis on two relevant pieces of the guitarist and orchestral repertoire.I found out a very strong link between the two genres, with Impressionism being very influenced by the traditional Flamenco style and the guitaristic idiomatic language and on the other hand the Spanish composers including in their compositions the new Impressionistic composing techniques and its new research on colors and timbres.Keywords: