Seven excerpts of modern jazz piano improvisations were selected to represent a range of perceived complexities. Audio recordings of the excerpts were played for 27 listeners who were asked to indicate their level of enjoyment on 7-point scales. Indications of enjoyment followed an inverted-U when plotted against perceived complexity of the music. Overall enjoyment was less for nonmusician listeners than for musician listeners. The inverted-U function was similar to the relations predicted by Wundt, over 100 years ago, and obtained by other investigators for responses to classical piano music and nonvocal New Age music. Assuming that perceived complexity generates comparable arousal levels, these findings substantiate optimal level of stimulation theory.