Attention-deficit hyperactivity disorder is one of the most common disorders that can occur in children. The symptoms are thought to result from a deficit in executive functions. This study investigated whether children with attention-deficit hyperactivity disorder subtypes differed in behavioural planning and response inhibition, two of the domains of executive functioning, from a control group without attention-deficit hyperactivity disorder symptoms. Furthermore, it examined whether the three attention-deficit hyperactivity disorder subtypes differed from each other in terms of performance. The sample ( n = 320) consisted of primary school children, aged between 6 and 14 years, from the Moletjie circuit (Limpopo). It consisted of an attention-deficit hyperactivity disorder group ( n = 160) and a control group ( n = 160). The Disruptive Behavioural Disorder rating scale was used to establish the symptoms of attention-deficit hyperactivity disorder. The Tower of London was used to measure planning ability, and the inhibition subtest (arrows and shapes) from the NEPSY-II (Developmental Neuropsychological Assessment, second edition) to measure response inhibition. Analysis of variance was employed to establish differences in subtype, gender, and age group. The results showed that children with the combined attention-deficit hyperactivity disorder subtype demonstrated significantly more deficits than the control group, in both behavioural planning and inhibition control. No significant differences between the hyperactive/impulsive and inattentive attention-deficit hyperactivity disorder subtypes and the control group were found. Gender and age did not influence performance with regard to planning and inhibition tasks. Correlations between planning behaviour and response inhibition were low, which suggests that they are distinct processes.