Matching of nonverbal behaviors in conversation, known as synchrony, is sometimes shown to predict the rapport between conversational partners. The aim of this study was to examine whether synchrony in vocal pitch between psychotherapists and clients is similarly associated with rapport. Recordings of psychotherapy sessions were analyzed to extract the synchrony in pitch of therapist and client speech, and these synchrony measures were then related to measures of the therapy relationship and treatment outcome. Results indicated that pitch synchrony did occur in the sessions but higher levels of synchrony were related to poorer therapeutic relationships and greater distress. These findings suggest that the vocal pitch of therapists and their clients may be of importance in understanding the psychotherapy interaction.