OBJECTIVE: The evaluation of the presence of parasites in semisolid and liquid sewage in Argentinian Patagonia in view of the fact that this is a restriction for its use. METHODS: The samples taken at 4 Domestic Sewage Plants were analyzed in accordance with Standard Methods for the Examination of Water and Wastewater, Environmental Protection Agency, World Health Organization and some other classifications. RESULTS: Only 2 of 6 semisolid samples analyzed had non-viable Ascaris lumbricoides eggs. Of the 10 liquid samples analyzed, only 2 did not contain eggs whereas the remaining ones had pathogens of categories I (Giardia sp., Hymenolepis nana and Enterobius vermicularis) and III (Ascaris lumbricoides, Ancylostoma duodenale and Trichuris trichiura). CONCLUSIONS: All semisolid samples turned out to be satisfactory for use as fertilizer as no viable Ascaris lumbricoides eggs were found in any of them. But only 6 of the liquid samples were satisfactory for use as they had no eggs or their concentrations was equal to or less than 1 egg per litre.