OBJECTIVE: To evaluate the effect of school-based nutrition interventions (SBNI) involving schoolchildren and adolescents in sub-Saharan Africa (SSA) on child nutrition status and nutrition-related knowledge, attitudes and behaviour. DESIGN: A systematic review on published school nutrition intervention studies of randomised controlled trials, controlled clinical trials, controlled before-and-after studies or quasi-experimental designs with control. Nine electronic bibliographic databases were searched. To be included, interventions had to involve changes to the school's physical and social environments, to the school's nutrition policies, to teaching curriculum to incorporate nutrition education and/or to partnership with parents/community. SETTING: Schools in SSA. PARTICIPANTS: School-aged children and adolescents, aged 5-19 years. RESULTS: Fourteen studies met our inclusion criteria. While there are few existing studies of SBNI in SSA, the evidence shows that food supplementation/fortification is very effective in reducing micronutrient deficiencies and can improve nutrition status. Secondly, school nutrition education can improve nutrition knowledge, but this may not necessarily translate into healthy nutrition behaviour, indicating that nutrition knowledge may have little impact without a facilitating environment. Results regarding anthropometry were inconclusive; however, there is evidence for the effectiveness of SBNI in improving cognitive abilities. CONCLUSIONS: There is enough evidence to warrant further trials of SBNI in SSA. Future research should consider investigating the impact of SBNI on anthropometry and nutrition behaviour, focusing on the role of programme intensity and/or duration. To address the high incidence of micronutrient deficiencies in low- and middle-income countries, food supplementation strategies currently available to schoolchildren should be expanded.