Autism is a developmental disability that affects children’s verbal and nonverbal behaviors with a ritualistic and compulsive way and it is significant before age three (APA, 1994; Berkeley et. al., 2001; Loovis, 2000). Also it is stated that children with autism have poor motor skills compared to their non-disabled peers (Winnick, 2000). Aquatic exercises provide a unique environment for special populations (Lepore, 2000). In addition, research shows that children with autism have positive experience and behaviors in aquatic exercises (Joyce-Petrovic et. al., 1994). In literature, it is stated that a constant time delay method was an effective way of teaching single and chain behaviors for special populations (Gast et. al., 1991; Mattingly and Bott, 1990; Tekin et. al., 2001). Halliwick’s swimming education is a recreational and rehabilitative program that teaches vertical and lateral rotation skills in swimming . This program emphasizes freedom and enjoyment from the water (Moran, 1996). Although there have been studies about the effects of constant time delay procedures in the literature, there had been no research especially for the effects of constant time delay procedures on Halliwick’s swimming education for children with autism. Therefore, the purpose of this study is to determine the effects of constant time delay procedures on Halliwick’s swimming education rotation skills of children with autism. A single subject multiple baseline model across subject design (Blackhurst et. al., 1994) was used to determine the effects of the intervention. Participants were three male children with autism, ages 7-9 years, and four trainers. Data were collected over the course of 10-weeks, with sessions three times a week. A single opportunity method (Snell and Brown, 2000) was used to determine the success rate of vertical and lateral rotation skills. The results of the study were analyzed via graphic illustrations. Results show that all subjects increased their correct rotation skills in a significant amount during the intervention phase. In addition, subjects maintained their successful rotation skills during the first, second, and forth weeks of generalization phases. The results of this study indicates that constant time delay procedure is an effective way of increasing and maintaining Hallivick’s swimming rotation skills of children with autism. However, this study has several limitations, such as the characteristics of participants, tests, and the measurements that were applied. Therefore, further studies should address the effects of constant time delay on different play skills, gender, ages and participants of children with autism.