Giardia intestinalis (G. intestinalis) and Helicobacter pylori (H.pylori) are two intestinal pathogens sharing the same mode of infection. This study determines the prevalence of G. intestinalis and H. pylori co-infection estimated risks and predictive factors for susceptibility to co-infection. Stool samples were collected from 801 patients suffering gastrointestinal symptoms and living in Greater Cairo. They were subjected to coproscopic examination for detection of intestinal parasites and copro PCRrestriction fragment length polymorphism (PCR-RFLP) and sequencing targeting the glutamate dehydrogenase (gdh) gene for Giardia. Positive samples for giardiasis were further subjected to coproimmunoassay to detect H. pylori coprontigen. Among 63 cases of giardiasis by both microscopy and PCR (84.1 % as-semblage B and 15.9% AII), 52.5% were co-infected with H. pylori. Co-infection was more frequent with assemblage B (50.9%) than assemblage A (40%). Among studied variables of assemblage type, gender, or harboring more than one parasite (polyparasitism), only school age children, was signifi-cantly associated (P value: 0.02) with Giardia and H. pylori co-infection. Physicians in Egypt must consider G. intestinalis and H. pylori as prevailing intestinal pathogens with predominance of Giardia assemblage B. Giardia and H. pylori co-infection is common in school aged children and modulates gastrointestinal manifestations. Intestinal parasitism and H. pylori association is complex and necessitates further genomic studies for a better understanding of the epidemiological and clinical impact of co-infection, as well as possible strategies for their treatment and control.