Reactions to music of 3 autistic children, 2 of them identical twins, were studied. There is considerable evidence that unique musical reactions constitute a general finding in autistic children. Investigations on 3 autistic children indicate that musical reactions are intimately bound with psychopathology; that reactions consist of a preoccupation and unusual absorption in music, a rote memory for melodies, a preference for singing over speech, a use of singing occasionally as a communicative means but more generally as an expression of an emotional state, and a response to music heard with rhythmical motions and easing of anxiety. There was also some evidence that improvement was associated with a decrease in intensity of interest in music. The possibility that the investigation of such musical reactions might provide further clues to the psychopathology involved, as well as new leads for therapeutic approaches, was discussed.These preliminary findings indicate a need for further investigation of an important feature in the clinical picture of infantile autism, namely, the reaction to music. Such study might well lead to further understanding of the condition. Determination of exact differences in the reaction of autistic children to music and the reactions of normal children would seem an important part of such a study. The possibility of a therapeutic application of music is suggested, but any statement as to its efficacy would be premature.