The conversion of tropical forest ecosystems to agro-pastoral ecosystems and other land uses continues unabated in Latin America. The present document constitutes a comparative study in which the degree of forest fragmentation through a 23-year period (between 1973 and 1996) was evaluated in two areas located within the same ecological region, but in two different countries (Colombia and Ecuador) which exhibit different patterns of human colonization. Landscape structure rates were used to evaluate the degree of forest fragmentation at both sides of the international border. Results show that the extent of forest fragmentation has been considerably higher on the Colombian side, suggesting that the natural ecosystems might be subject to higher degradation pressures, with potentially important detrimental effects on the abundance and distribution of the biota.