This study examined if listening to music will improve the accuracy of blood pressure (BP) readings in children with Williams syndrome (WS). Fifty-two participants (7-12 years) were randomly assigned to a music or non-music group. BPs were obtained at two time points. There was a significant decrease in both systolic and diastolic BP from Time 1 to Time 2 for everyone. Participants from the music group had lower systolic BP readings at Time 2 than participants in the non-music group (Cohen's d = 0.33). Systolic BP readings were approximately 3.8 mmHg lower in the music group. Music may be beneficial in obtaining more accurate systolic BP readings in children with WS.