Co-infection between intestinal parasites and Plasmodium falciparum is very frequent in inter tropical zone. Our study carried out in the North of Senegal (zone of high prevalence of schistosomiasis) aimed at measuring the influence of the carriage of intestinal parasites on the intensity of malaria infection. The Plasmodium falciparum densities were significantly higher during Plasmodium falciparum/Schistosoma mansoni and Plasmodium falciparum/Ascaris lumbricoides co-infection in children under 14 years old. Other intestinal parasites did not seem to have negative influence on the intensity of Plasmodium falciparum infection.