Objectives : The purpose of the present study was to determine whether kata training leads to reductions of stereotypic behaviors in Asperger syndrome. Method: In this single-subject study, three boys with Asperger syndrome were required to exercise Heian Shodan kata for 12 weeks. Changes in the severity of stereotypy was assessed at one-week intervals during the experimental phase and one month after termination of the intervention using multiple baseline method. The Gilliam Autism Rating Scale-Second Edition (GARE-SE) was used to measure stereotypic behaviors. Analysis of within and between subject effects was done using diagrams for stability envelope and data trending. Results: Training in Heian Shodan Karate decreased stereotypy in all three participants [Percentage of Non-overlapping Data (PND)=83.33% for first and second participants, PND=91.67% for the third participant] and this reduction was maintained one month after termination of the intervention. Conclusion: Long-term kata training resulted in reductions of stereotypic behaviors in three boys with Asperger Syndrome. However, research with larger sample sizes is required to examine the effectiveness of this intervention and improve confidence in the current findings.