Autism spectrum disorder (ASD) is a complex heterogeneous neurodevelopmental disorder. Risperidone and Aripiprazole appear to be effective in associated behavioural problems with ASDs, including irritability, aggressiveness, hyperactivity, self-injurious behaviour, and stereotypies. In our case, new-onset diurnal enuresis was observed as a side effect after risperidone use. New-onset diurnal enuresis improved when risperidone was stopped, but recommenced when aripiprazole was added to treatment. However, all symptoms of enuresis resolved when the aripiprazole dosage was reduced. In contrast to some reports in which aripiprazole was used in the treatment of enuresis, our case is different in that it led to diurnal enuresis.