To demonstrate the infection of pigs with helminths in the Mekong Delta, an investigation into the actual conditions was carried out in the area. A total of 87 pigs from 38 farms were examined for the presence of the helminths. Eggs of common nematodes (Ascaris suum, Metastrongylus spp., Oesophagostomum spp., Trichuris suis and Strongyloides ransomi) present in Japan, were detected. Especially, since the morbidity rate of A. suum infection was very high, the effect of the Ascaris infection on pig growth was investigated. As a result, economic loss was estimated at US$2.0/head. In addition, infection with Fasciolopsis buski, which dose not occur in Japan, was detected in 4 pigs from 4 small farms. These 4 pigs were given water spinach as a supplemental feed. It was suggested that this vegetable played an important role in F. buski infection and that the fluke infection was one of the zoonoses. Infection with this fluke in human can be anticipated, because most of the inhabitants ate this vegetable in the Mekong Delta.