The Peruvian Amazonian basin (977 920 km2, 76% of the surface of Peru) is supposed to bring to Brazil an important volume of water. However, the discharge of the Peruvian Amazon was not known until now. In this work, the discharge at Tamshiyacu, the only gauging station available in the Peruvian Amazon basin, was calculated (1969-2005) using daily level flow data at Tamshiyacu (1983-2005) and at Iquitos (1969-2005, 50 km downstream), and gauging data measured by ADCP at Tamshiyacu since 2001. The annual average discharge at Tamshiyacu, is 25 000 m3 s-1. Monthly rainfall data from 234 raingauge stations was used to calculate the depth of runoff (1964-1997). The average precipitation is 1600 mm year-1. The annual rainfall/discharge relationship for the common 1970-1997 period is high (r 2 = 0.77). During this period, decreasing tendencies are observed: -0.83% and -0.81% for rainfall and discharge, respectively. Copyright © 2006 IAHS Press.