Abstract : The researches developed during this study gives answers about three important questions: What are the annual and seasonal cycles, as well as interannual and intra-seasonal variability in the medium and long term hydrological cycle over the basins of Huallaga and Ucayali rivers? What are the water resources available in the basins of Huallaga and Ucayali rivers? What is the impact of the climate change on the hydrological cycle of Huallaga and Ucayali rivers? First, we describe the main features of the basins of Huallaga and Ucayali rivers, as well as the hydrological database used an we put in evidence a warming in our zone of study (estimated at +0.09°C per decade). Moreover, the ruptures observed in the series of average temperature at the end of the Seventies are in accordance with the sequences of “El Niño”. We showed a negative correlation between the temperatures and the index of the Pacific (Southern Oscillation Index, SOI). On the other hand, no tendency is highlighted in the precipitation series. Nevertheless, approximately 10% of the stations in our area of study present significant ruptures during the 1991-2000 decade. Then, the production of water resources in the basins of Huallaga and Ucayali rivers is evaluated over 7 sub-basins: 6 located in the Ucayali basin and one located in the Huallaga basin. To quantify water resources, we use two hydrological models at monthly step (GR2M and MWB3). The use of water holding capacity data of FAO soils (maximum, mean and minimum) as input of the hydrological models, contributed to propose physical interpretations to these models. The optimal parameters obtained by calibration procedure reproduce reasonably well the flow observed in the selected basins. The impacts of climate change on hydrology were evaluated using as climatic data the outputs of the IPCC models (BCM2, CSMK3 and MIHR), corresponding to the scenarios A1B and B1. The annual flows simulated in the 2008-2099 period suggest that the impacts of climate change on hydrology vary with the basin, the hydrological model chosen, and the scenario: The Requena sub-basin is characterized by an increase (respectively a reduction) of flow using GR2M model (respectively MWB3) considering the A1B and B1 scenarios. The Chazuta, Maldonadillo and Pisac basins exhibit flows decreasing while the basins of Puerto Inca, Tambo and Mejorada show flows increasing. The changes simulated in monthly flows over the 2008-2099 period suggest an increase for all the sub-basins, except the Pisac basin. July, August and September are in general the months characterized by the most marked changes, with an increase in flows for Requena, Chazuta, Puerto Inca, Maldonadillo and Tambo basins.