ESTIMATES published in the past 20 years of the sediment load delivered to the sea by the Amazon River range from 4 to 10 × 108 tonnes yr−1 Estimates published around 1960, when few data were available on either the sediment concentration or the river discharge, were in the range 9–10 × 108 tonnes yr−1 (refs 1, 2). Estimates published in 1967 and 1968, after significant new data had been collected, were in the lower range of 4–5 × 108 tonnes yr−1 (refs 3, 4). Our more comprehensive data collected mostly since 1970 (and especially in 1977) suggest that the earlier higher estimates may have been more nearly correct. We show here that the mean annual load of suspended sediment at Obidos, Brazil is between 8 and 9 × 108 tonnes yr−1. Most of this sediment is discharged onto the continental shelf.