Intestinal parasites account for the majority of parasitic diseases, particularly in endemic areas. Most are transmitted via contaminated food. Because of increased immigration and travel, enteric parasitoses are now distributed worldwide. Between May 2006 and December 2008, we examined stool specimens from 5,351 patients (4,695 Italians, 656 non-Italians) for ova and parasites using microscopy, culture techniques, and molecular methods. Stools from 594 patients (11.1%) were contaminated and for all patients samples combined, a total of 700 intestinal parasites were counted. Ninety of the 594 infected patients had more than one parasite in their stools. Parasites causing intestinal disease occurred in 8.8% of patients. The prevalence was over twice as high among non-Italians (26.8% vs 8.9% in Italians, p<0.001) and higher in males (13.0% vs 9.5% in females, p=0.003). Most isolates were pathogenic protozoa, including in decreasing order of frequency: Blastocystis hominis, Giardia intestinalis, Entamoeba histolytica, and Cyclospora cayetanensis. The latter two species tended to be more common in Italians, although not at significant level (3.6% (15/418) vs 1.7% (3/176) in non-Italians, OR: 2.15; 95%CI: 0.60–11.70, p=0.22). Helminthes were found in 28 patients, mainly non-Italians (5.7% (10/176) vs 4.3% (18/418), OR: 1.34; 95%CI: 0.54–3.13, p=0.47). Ascaris lumbricoides and Hymenolepis nana were the most common. Strongyloides stercoralis, Enterobius vermicularis, Taenia spp. and Trichuris trichiura were also found. Intestinal parasites are a serious problem in developing countries, but should not be underestimated in industrialised countries.