Background Anxiety is a common problem for children with autism spectrum disorder (ASD). Recent research indicates that intolerance of uncertainty (IU) may be an important aspect of anxiety for this population. IU is the belief that uncertainty is upsetting, and not knowing what is going to happen is negative. There is little known about the phenomenology of IU in children with ASD. We therefore present data from parent focus groups exploring this concept in children with ASD. Methods Participants were asked to differentiate IU from dislike of change and fear, and to discuss examples of IU and the strategies they use to manage it. Their experiences of IU and strategies are presented. Results IU was evident across novel and familiar situations and parents used a variety of strategies to manage IU. Their experiences of IU and strategies used are presented. Conclusions Participants were able to identify and provide examples of IU suggesting that it is a recognizable construct among children with ASD.