Three specific dimensions of potato land use were researched to gain insights into possible contemporary changes affecting the in situ conservation of potato genetic resources: land use tendencies, rotation designs and their intensity, and sectoral fallowing systems. The main research method involved participatory cartography combined with in-depth consultation through interviews and focus group meetings with members of eight Andean highland communities. Land use tendencies between 1995 and 2005 show that the total cropping area dedicated to improved cultivars has grown fast whereas the area reserved for native-floury and native-bitter cultivars has remained more or less stable. Reduced fallow periods for existing fields and the gradual incorporating of high-altitude virgin pasture lands sustain areal growth. Although areas of improved cultivars are proportionally growing fastest at extremely high altitudes between 3900 and 4350 m, overall cropping intensity or fallowing rates are inversely related to altitude. No evidence of a straightforward replacement of one cultivar category by another was found. Inquiry into the dynamics of sectoral fallow systems over a 30-year period evidences the gradual disintegration and abandonment of these systems rich in cultivar diversity. Where sectoral rotation designs survive, local innovations have been adopted. © 2010 Taylor & Francis.