The Amazon basin represents 76% of the area of Peru. From north to south, the Andean tributaries of the Amazonas River in Peru are: the Napo River (100 520 km2, 6300 m3 s-1), the Marañón River (360 550 km2, 14 700 m3 s-1) and the Ucayali River (360 490 km2, 13 800 m3 s-1). The total suspended sediment yield exported from Peru to Brazil by these rivers is about 450 × 106t year-1 for the 2004-2006 period (12% from the Napo River, 40% from the Marañón River and 48% from the Ucayali River). As the Amazon flood plain traverses the Andean piedmont and reaches its mouth, sediment yield increases along the Napo and Marañón rivers. This suggests the occurrence of erosion processes in the lowlands as observed in Ecuador, rather than the occurrence of sedimentation as observed along the Madeira River in Bolivia. At all the study stations, discharge and suspended sediment yield show a very high degree of seasonal variation. Copyright © 2007 IAHS Press.