This paper describes the Evolutionary Jazz Improvisation (EJI) system for creation of jazz harmony and jazz solo improvisations based on evolutionary algorithms with automatic evaluation. The evaluation function is implemented using score calculation based on specific events recognized in the chord progression and solo line, and alignment to different optimal intensity increase and relaxation curves. The evaluation function is based on the author’s solo analysis of 73 great masters’ solo characteristics and their techniques used for build-up of jazz solos. The results have been evaluated by our live jazz group and used in jam sessions, some of which have been recorded and made available for listening at the links given later.