Abstract Background Many ecosystems have developed in the presence of agriculture and cessation of management resulting from land abandonment can have significant ecological impacts. Around 56 percent of the utilised agricultural area of the European Union is classified as ‘less-favourable areas’ and much of this is mountainous. The small-scale and extensively managed farmlands that are common in mountain areas are particularly vulnerable to marginalisation and abandonment. We conducted the first systematic global mapping of evidence to inform stakeholders and policy makers of the potential impacts of farm land abandonment in mountain areas. Methods Evidence was collated from a range of academic literature databases and grey literature sources. Identified articles (8,489) were screened for relevance at title, abstract and full text using predefined inclusion criteria set out in a published protocol. Relevant studies (165 across 189 articles) were then mapped using predefined coding and critically appraised for internal validity (i.e. susceptibility to bias). Results Mapping identified a number of interesting themes in the evidence base: the majority of research was undertaken in arable and mixed farming systems; large evidence bases were found in China, Spain and Italy; studies were mostly observational with spatial/successional comparators; biodiversity, soil and vegetation were most frequently studied. Several knowledge gaps were identified: including outcomes (socioeconomics and environmental hazards), regions (key mountain ranges including the Himalaya), and specific outcome-region groups (e.g. vegetation and soil measures in the UK). Several deficiencies in methodology were identified across studies: a lack of replication; non-random sample selection; lack of methodological detail (including details of spatial scale, replication, and sample selection). Discussion Systematic mapping has produced a searchable database of studies relating to high altitude farmland abandonment. The map identifies a number of potential areas for fruitful future synthesis, for example research on biodiversity, soil and vegetation in the Loess Hilly Plateau in China, and soil research in Spain. Such synthesis would be rapid given the effort expended here in identifying and screening relevant articles. It also points to several areas that were under-represented in the literature, such as natural hazards (avalanche, fire and flood risk), that would potentially benefit from increased primary research.