This study determined the prevalence of intestinal parasites, particularly pathogenic Entamoeba sp. (E. histolytica), in patients attending three hospitals in Jeddah City, King Abdulaziz University Hospital, King Abdulaziz Hospital and King Fahad Hospital for gastro-intestinal troubles. 186 stool specimens were examined microscopically for parasites and by ELISA kit (E. histolytica II) for true E. histolytica. 83 samples (44.6%) were positive by microscopy for at least one parasite. Of which, 23 (12.4%) showed two parasites and 15 (8.1%) three parasites. Eight different parasite species were identified. The most prevalent were E. histolytica/dispar (n = 26, 31.3%) and Giardia lamblia (n = 13, 15.7%). Others were Blastocytosis hominis (n = 12, 14.5%), Entamoeba coli (n = 11, 13.3%), Trichuris trichuria (n = 8, 9.6%), Endolymax nana (n = 6, 7.2%), Hymenolepes nana (n = 4, 4.8%) and Chilomastix mesnili (n = 3, 3.6%). Only five stool samples (19%) from those identified by microscopy to contain E. histolytica/dispar, were E. histolytica positive by E. histolytica II ELISA. For the first time to the authors' knowledge the true prevalence of E. histolytica in Saudi Arabia was 2.7%. E. histolytica II ELISA proved to be a highly useful technique to differentiate pathogenic E. histolytica from non pathogenic E. dispar.