The aim of this systematic review is to summarise the existing literature regarding management of residual obstructive sleep apnoea post adenotonsillectomy in children with Down Syndrome. PubMed, EMBASE, Cochrane and Scopus were searched to retrieve all studies published up to May 2020 regarding the management of obstructive sleep apnoea in children with Down Syndrome post adenotonsillectomy. Eight studies were identified including five retrospective studies, two prospective and one case series. Five articles addressed surgical treatments only, two articles addressed hypoglossal nerve stimulation and one article addressed both surgical and medical treatments. Findings were similar across most studies where the obstructive apnoea hypopnoea index (oAHI) was reduced post intervention however given the heterogeneity in methodology and patient demographics, results were not directly comparable. Limited evidence was found regarding BMI and outcome post-surgery, suggesting that those who were normal weight or overweight had a significant reduction in the oAHI, compared to those who were obese. The most optimal treatment for the management of residual obstructive sleep apnoea remains uncertain. There are various treatment options described in the literature, however, they have not been thoroughly studied, with only eight relevant articles found. Studies comparing outcomes following different treatment interventions and using consistent parameters are required to gain further understanding of the most optimal treatment for residual obstructive sleep apnoea in this population. Understanding if specific phenotypic features, such as weight, influence response to therapy will also be important. This information will help to develop treatment algorithms, which will assist in improving patient care by directing treatment and ensuring a more consistent approach to overall management. The high prevalence of residual obstructive sleep apnoea in children with Down Syndrome following first line treatment makes this a clinically important area to target in this particular cohort of children to avoid long term complications of untreated OSA. [ABSTRACT FROM AUTHOR]