The assessment of autism in individuals with mild intellectual disabilities (MID) is complicated because of the overlap between autistic traits and intellectual limitations. Impaired social emotional reciprocity is a core diagnostic criterion for autism. However, it is unknown whether reciprocal behaviour differs between MID individuals with or without an autism spectrum disorder (ASD). This study explored differences in reciprocal behaviour of 35 children and adolescents with MID (intelligence quotient 50-85): 15 with ASD (ASD-MID) and 20 with typical development (TD-MID) using the Interactive Drawing Test (IDT). ASD-MID participants showed a lower quality of reciprocal behaviour compared with TD-MID participants. The difference in quality of reciprocal behaviour between ASD-MID and TD-MID participants was not significantly related with Peabody Picture Vocabulary Test scores and thus not attributable to verbal capacity. The IDT is likely to reflect the child's inclination to display reciprocal behaviour in everyday situations, as its scale scores were meaningfully associated with the level of social cognition assessed with the Social Responsiveness Scale. Thus, the IDT seems well suited for measuring impairments in reciprocal behaviour in children and adolescents with MID.