This survey completes our earlier work on the evolution of the Amazon discharge at Óbidos from 1903 to 1999. In the Amazon basin above Óbidos (4,680. 103 km2), 341.103 km2 were deforested between 1976 and 2003. The impact of this deforestation on the mean annual discharge was estimated using a water balance approach from 1940 to 2003. The evolution of the runoff coefficient indicates that there was a 5% increase in the mean annual discharge over the 22 years from 1981 to 2003. The number of strong floods was five time higher during this period than it was before. On the other hand, it seems that there is no influence of the deforestation on the low flows.