Severe hypodontia (≥6 missing teeth) is associated with aesthetic and functional problems. Its presentation is heterogenic, and a variety of treatment modalities are used resulting in different treatment outcomes. As there is currently no standard treatment approach for patients with severe hypodontia, the literature was systematically reviewed with the focus on treatment outcomes. Medline, Embase and The Cochrane Central Register of Controlled Trials were searched (last search 24 August 2015). This was completed with a manual search of the reference lists of the selected studies. To be included, studies had to describe dental treatment outcome measure(s) in patients with severe hypodontia; there were no language restrictions. The methodological quality was assessed using MINORS criteria. Twenty-one studies were eligible, but the diversity in type and quality did not allow for a meta-analysis; seventeen studies had a retrospective design; sixteen studies described the results of implant treatment. Treatment with (partial) dentures, orthodontics, fixed crowns or bridges was sparsely presented in the eligible studies. Implant survival, the most frequently reported treatment outcome, ranging from 35·7% to 98·7%, was influenced by ‘location’ and ‘bone volume’. The results of implant treatment in severe hypodontia patients are promising, but due to its heterogenic presentation, its low prevalence and the poor quality of the studies, evidence-based decision-making in the treatment of severe hypodontia is not yet feasible, thus prompting further research.