Attention-Deficit/Hyperactivity Disorder (ADHD) is a persistent pattern of behaviours characterized by inattention, hyperactivity and impulsivity. This study evaluates the effects of a tailored Incredible Years Teacher Classroom Management (IYTCM) programme aimed to improve participating children’s on-task behaviour and literacy performance, as well as reducing ADHD symptoms in a group of 6 to 10 year old children with ADHD in Addis Ababa, Ethiopia. Nine children, who were identified with ADHD symptoms on the basis of teacher and parental reports, were involved in the IYTCM-ADHD programme. The children’s behaviour symptoms were assessed using the Conners 3-T, Conners 3-P(S), SESBI-I, ECBI and SDQ. Ten teachers received the IYTCM-ADHD training in a full-day session once a week for 6 weeks. The children received individual behaviour plans implemented by their teachers with close supervision. A single-subject design was implemented to record the behaviour changes over time: at baseline, during teacher training with the IYTCM-ADHD programme, and at both immediate and long-term follow-ups. The on-task behaviour of children with ADHD and normative comparison children was recorded using Behavioural Observation of Students in Schools (BOSS). In addition to visual analysis, a non-parametric test Percentage of All Non-Overlapping Data (PAND) was used to examine the magnitude of effect in each child. The result of the study indicated that on-task behaviour of all the children with ADHD improved an average of 78% during the teacher training and this maintained during the follow-up phases. The children’s on-task behaviour also generalised to classrooms with non-trained teachers. Visual analysis indicated that the children’s behaviour was maintained during the follow-up phases. The pre- and post-intervention analyses of children with ADHD showed a significant effect of the intervention as a group. Clinical significance was obtained for more than half of the children on teacher reports of ADHD symptoms and conduct problems after the intervention. The literacy performance of all children with ADHD improved at the conclusion of the study. In light of the findings, limitations and implications for future research were discussed.