A quantitative and constraint-specific approach to assess the potential impact of new agricultural technology is described and applied to frost resistant potato cultivars for the Altiplano (Peru and Bolivia). The approach uses geo-referenced databases and a simulation model. Calculations are made for small grid cells, and no arbitrary delimitation of agroecological zones is needed. The LINTUL potato growth :simulation model was adapted to incorporate the effect of frost damage on yield. High-resolution grids of monthly climate data were created for a number of variables, including absolute minimum temperature and its standard deviation, and used as input for the simulation model. The model was run for each grid cell, using a standard potato cultivar for which frost resistance parameters were changed in increments of -1 degreesC. A geo-referenced database of potato distribution was used to process the output of the simulation model to calculate potato-area weighted results. When frost resistance increases from -1degrees C (current level) to -2 or -3degreesC, average potato yield increases by 26 and 40%, respectively. After that, the effect tapers off and a further increase in resistance leads to only a small increase in simulated potato yield. (C) 2003 Elsevier Science Ltd. All rights reserved.