This study examined the efficacy of Parent Child Interaction Therapy on alleviating behavioral issues among children with Autism Spectrum Disorder (ASD) as well as its efficacy in improving the mother s parenting stress, depression and parent-child interactions. Twenty mother-child dyads were randomly assigned to either the experimental group or the waitlist control group. The PCIT program was conducted in 12 sessions, once a week for an hour in the experimental group. Primary findings were followings: first, following manualized PCIT treatment, mothers reported a decrease in the level of children s disruptive behavior, parenting stress, and depression. Second, the frequency of positive interactions increased while the number of negative interactions decreased. Third, after the completion of the PCIT program, mothers in the experimental group reported high levels of satisfaction with the intervention. Treatment gains were maintained at 3-6-12month follow-up assessments. This study gives evidence to support PCIT as an efficacious intervention program for Korean families who have young children with ASD.