Two sets of 5-year long integrations were performed with the GLA GCM with a simple biosphere model (SiB) to delineate the influence of Amazonian deforestation on the local as well as basinwide circulation and rainfall. The control case invoked a normally forested Amazonia, while the deforestation case distinguished the partially deforested Amazonia (until the year 1988) as savanna. Except for this one difference, all other initial and the prescribed boundary conditions were identical in both integrations. A differential analysis of these two simulations revealed the following. (1) There was a large decrease in evapotranspiration (1.15 mm d-1, roughly 33%) in the deforested region, while the basinwide decrease was only 0.24 mm d-1 (roughly 8%). (2) The associated decrease of precipitation in the deforested (basinwide) regions was about 0.30 (0.168) mm d-1. A precipitation decrease that is smaller than evapotranspiration decrease reflects a mitigating influence of increased moisture convergence, particularly within the boundary layer that gets warmed by the increased surface fluxes of sensible heat and longwave radiation. This implies that precipitation decrease in response to the 1988-level of Amazonian deforestation could be reversed, i.e., reforestation is likely to emerge if the anthropogenic pressures were eliminated and deforestation were forestalled. (3) The changes in the surface wind and rainfall patterns together with increased runoff and surface temperature indicate potential hydrological as well as ecological consequences of deforestation. In our simulations, only small regions of the Amazon basin produced precipitation and circulation changes at 90% or better statistical significance level. This is a consequence of a more realistic deforestation in Amazonia as compared to the total deforestation scenario used in previous studies. ¿ American Geophysical Union 1996