Surface sedirnents frorn the contincntal slope and rise off North-West Africa between the Canary Islands and the Cape Verde Islands are mainly composed of silt-sized material (2-63 µm). A number of sampling profiles were run normal to the coast and the cornposition of the silt [ractior, was determined quantitatively by scanning elcctron microscope analysis. The carboriate portion of the sediment was found to be nearly exclusively of biorcnic origin. The most imponant comributors are p l.mktornc foraminifers and coccoliths with minor contributions derived from pteropods. Plankton-produced biogenic opal such as diatoms and radiolarians play a very minor role. The high production rates of opal-siliea plankton which exists in the surface waters of the NW-African upwelling system does not give rise to corresponding incrcases of opal accumulation in the bottorn sediment. Benthic producers consist mainly of foraminifers and molluscs but the entire input from benthir producers is extremelv small. An exception to this occurs in the prodelta sediments of the Senegal river. Downslopc partiel transport is indicated by the occurrence of shallow-w.uer coralline algae, ascidian sclcrites a nd cliona boring chips and can be traced as far down as the continental rise. The non-carbonate silt fraction mostly consisis of quartz which is derived as eolian dust from the Saliern desert by the Harnrattan and the Nli-Trade-wind systern. The percentage of carbonate in the surface sediments directly iudicates the relative proportioris of autochthonous biogenie components and terrigenous allochthonous quartz panicles.