Land tenure in many parts of Brazil remains uncertain and controversial. These problems have recently beenexacerbated by changes in the legal framework regulating protected areas and the land market. A particularchallenge facing attempts to improve land tenure security and governance in Brazil is the lack of a single,integrated assessment of all types of lands. Here we address this problem and present afirst, integrated map ofBrazilian land tenure encompassing all official data sources pertaining to both public and private lands. Of thetotal (8.5 million km2) 36.1% of all lands are public (with 6.4% officially undesignated), 44.2% are private, and16.6% are unregistered or with unknown tenure. Strikingly, overlaps among land tenure categories sum to 50%of the registered territory of Brazil. A clearer understanding of uncertainties in land tenure, and the spatialdistribution of those uncertainties can help guide research and public policies focused on minimizing landconflicts and strengthening governance and territorial planning to improve economic, environmental and socialoutcomes from land use in Brazil Ver menos