BACKGROUND: Elevated levels of poor mental health have been recorded amongst populations affected by armed conflict. The aim of this study was to systematically review existing evidence on the factors influencing general psychological health of conflict-affected populations in low- and middle-income countries. METHODS: Quantitative studies that described statistically significant associations with general psychological health of adult conflict-affected persons in low- and middle-income countries were included. Bibliographic databases and humanitarian agency websites were searched, and a screening, selection and review process was applied. The findings are described using commonly recurring categories of demographic characteristics, socio-economic factors and exposure to traumatic events. RESULTS: Fifteen studies met the inclusion criteria. Factors with an association with worse general psychological health were demographic factors of gender (women), older age and not being married; socio-economic factors, such as low education level, low income and assets, not working, residential status, living conditions and insecurity; and a number of violent and traumatic events including forced displacement - particularly internal displacement. CONCLUSIONS: The evidence base was weak and methodological limitations were noted. Further research is required to better understand the factors influencing general psychological health amongst conflict-affected populations in low- and middle-income countries.