The distribution of suspended matter was studied in the Gulf of St. Lawrence. A three-layer distribution was found. In the surface layer, which was less than 50 m deep, concentrations of suspended matter ranged from 0.10 mgl−1 to 2.9 mgl−1. A relationship to the surface circulation pattern existed with the highest concentrations occurring in the low salinity surface outflow from the estuary. In the intermediate layer, which extended down to about 50 m above bottom, the concentrations of suspended matter ranged from 0.05 mgl−1 to 0.1 mgl−1. The intermediate layer, characterized by these concentrations, was found in all the deep areas of the Gulf. Concentrations of 0.1 mgl−1 to 0.4 mgl−1 were found in the bottom layer, with highest values occurring near the estuary.Budget calculations indicate that 5 × 106 tons/yr of suspended matter enter the Gulf from the rivers, and that erosion of the coastline and reworking of sediments are significant processes which contribute about 10.5 × 106 tons/yr of suspended matter. The net seaward transport at Cabot Strait is estimated as 5.5 × 106 tons/yr.