The potential impacts of a hypothetical climate change induced by a rise of the concentration of greenhouse gases on the water cycle of the Sagana River basin (Central Kenya) have been assessed. For this purpose, by fitting the IRMB daily conceptual hydrological model to this basin, a water balance assessment for the period 1978–1988 was performed. The model parameters having been optimized, climate change scenarios were adopted, mainly from General Circulation Models. Three scenarios differing only by rainfall modification were considered (i.e. rises of 0%, 5% and 10%). New water balances under those assumptions were compiled and a sensitivity study performed. Conditional to the adopted climate change scenario, the results showed a general tendency towards improved water resources for this equatorial basin during the dry seasons in the 10% rainfall rise scenario. On the other hand, a reduction of the water resources was simulated if no rainfall increase was adopted in the climate scenario. Negative impacts could be feared in this case. The scenario with an intermediate 5 % rainfall increase led to a position of status quo.