An investigation of helminths in the Norway (brown) rat, Rattus norvegicus, and roof rat, Rattus rattus, from Chiang Mai Moat during May to August 1995, was done. Thirty-three out of thirty-eight trapped rats were infected (86.84%); 16 R. norvegicus (100%) and 17/22 R. rattus (77.27%). The rat was infected with 10 helminth species: 4 trematodes, Centrocestus sp (2.63%), Echinostoma ilocanum (10...