SummaryThe parasitologic investigation performed without clinical orientation in a routine laboratory allowed to identify the most common parasites, often cysts of Protozoa, using a minimal technique. A more accurate investigation (e.g.: concentration, extraction and flotation) was hampered by a too large number of systematic specimens. The use of an immersion objective improves the detection and identification of cysts of protozoa. There is still some controversy on the virulence of small amoebae, flagellates,BlastocystisandEntamoeba coli, the infection being often massive. AIDS should predispose to new parasitic diseases such as cryptosporidiosis and strongyloidosis. A careful examination of stools for parasites has become mandatory in view of the wide geographical origin of patients with a parasitic disease.