This paper presents the research performed in the wet Andean páramo ecosystem in order to study the land use change impacts on its hydrology, using small paired catchments. The research results revealed that pine plantations produce a decrease of annual water yield as a consequence of increased evapotranspiration. On the other hand, livestock grazing does not seem to affect the hydrological response, primarily due to the low animal density. The main impact of cultivation is the reduction in the regulating function of the catchment, with a large increase in the magnitude of peak flows and a reduction of base flows. Furthermore, research results revealed that vertical infiltration through the soil is dominant under wet conditions, whereas preferential flow within the organic horizon to the underlying mineral horizon is dominant during low intensity rains. Saturated excess surface flow is observed only during long rain events; otherwise near surface lateral flow in the organic layer occurs. There is no evidence of Hortonian flow. Copyright © 2010 IAHS Press.