In Dakar, through histopathological biopsies, the author looked for duodenal alterations in four parasitosis: giardiasis, strongyloidiasis, hookworms and ascaridiosis. He gives an overall survey on malabsorption in relation with intestinal parasitosis, including intestinal capillariosis and coccidiosis. He recalls basic concepts concerning each of these parasitic diseases, with a special mention to mucosal invasion and endogenous self reinfection during some parasitosis; he also emphasizes the importance of some diagnosis techniques (such as examination of duodenal fluid in relation to giardiasis). Anatomical lesions (villi atrophia and chorion cellular infiltration) were the starting point to study such as intestinal malabsorption. But these lesions are neither specific nor regular. Other causes must be determined such as direct action of the parasite, bacterial overgrowth, exudative enteropathy. The role played by host factors seems to be of the utmost importance in giardiasis and strongyloidiasis (antibody deficiency proteinic malnutrition). The part played by the parasite biomass is unquestionable in hookworm disease (hypoalbuminuria, anemia) and a great number of worms in ascaridiasis worsens a preexisting condition of malnutrition. Finally, intestinal parasitosis, with a special mention to giardiasis and strongyliasis, may be responsible for a malabsorption syndrome. They must be identified through reliable diagnosis tests, prior to referring to "idiopathic malabsorption syndrome in Tropical areas".