The alpine Rhone, discharging to Lake Geneva, was sampled for suspended solids over a period of twenty months by direct pumping and centrifugation. Sampling was carried out at the rivermouth every two weeks, and once a month in December, March, May and August at five other points in the watershed. On the basis of texture, major elements, trace metals and forms of phosphorus, the suspended solids appeared to be relatively homogeneous, with transport showing but little influence in their composition. The suspended solids may be divided into two distinct types. One of the main characteristics of the first type are heavy concentrations of Apatitic lnorganic Phosphorus (AIP) during the high Flow associated with the glacial melt. The second type is mainly characterised by high levels of Non Apatitic lnorganic Phosphorus (NAIP) found in winter and early spring. NAIP is produced by agricultural and urban soil run-off and point sources associated with sewage treatment plants when the Rhone glacier is frozen and not contributing to the river flow. Although the total phosphorus load of the Rhone is predominant compared with that of the other tributaries to Lake Geneva, its 69% of non bioavailable AIP indicates that the Rhone plays a lesser role in the trophic budget of the lake than first thought.