Purpose : There is a lack of research on this field in the Republic of Korea, especially those that have seen the effect of interaction between siblings through sensory integration therapy (SIT). Therefore, this study sought to find out the effectiveness of SIT with siblings through the Revised Knox Preschool Play Scale (RKPPS) and playtime. Methods : The experimental group consisted of 10 disabled children, and 10 normal siblings of the disabilities joined the program as a helper. In addition, 10 children with disabilities conducted the intervention as a control group. The difference between the experimental group and the control group is whether they participate with their sibling or not during the intervention period. The present study was conducted a SIT for 40 minutes per week for the experimental and the control group and then had 10 minutes of an interview with the parents of children with disabilities. A total of 10 programs were implemented for 10 weeks. Results : The experimental group showed statistically significant differences in space management, material management, pretense/symbolic, participation, and total scores. The control group showed significant differences between pre and post results in the participation and the total scores. The experimental group and the control group showed significant differences in the pre-post comparison results. The comparison of post-intervention between both groups of the RKPPS and playtime results showed a statistically significant increase in the experimental group. Conclusion : The sibling SIT showed better play level and time than the individual therapy. However, comparisons before and after the intervention in the level of play showed significant results only in participation and total scores in the control group. Clinically, it is recommended to make good use of sibling relationships when applying SIT, and if that is not possible, continuous observation is needed that children who received treatment become familiar with the environment in which they can be treated.