Abstractobjectives Malnutrition contributes to paediatric morbidity and mortality in disasters and complex emergencies, but summary data describing specific nutritional interventions in these settings are lacking. This systematic review aimed to characterise such interventions and their effects on paediatric mortality, anthropometric measures and serum markers of nutrition.methods A systematic search of OVID MEDLINE, Cochrane Library and relevant grey literature was conducted. We included all randomised controlled trials and observational controlled studies evaluating effectiveness of nutritional intervention(s) on defined health outcomes in children and adolescents (0-18 years) within a disaster or complex emergency. We extracted study characteristics, interventions and outcomes data. Study quality was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria.results A total of 31 studies met inclusion criteria. Most were conducted in Africa (17), during periods of conflict or hunger gaps (14), and evaluated micronutrient supplementation (14) or selective feeding (10). Overall study quality was low, with only two high and four moderate quality studies. High-and medium-quality studies demonstrated positive impact of fortified spreads, ready-to-use therapeutic foods, micronutrient supplementation, and food and cash transfers.conclusion In disasters and complex emergencies, high variability and low quality of controlled studies on paediatric malnutrition limit meaningful data aggregation. If existing research gaps are to be addressed, the inherent unpredictability of humanitarian emergencies and ethical considerations regarding controls may warrant a paradigm shift in what constitutes adequate methods. Periodic hunger gaps may offer a generalisable opportunity for robust trials, but consensus on meaningful nutritional endpoints is needed.