Result of a survey on the acute diarrhea outbreaks indicated that morbidity and mortality ratio in the suckling pigs were very high (93.94 percent and 81.67 percent, respectively). These two ratios were gradually reduced by the age of pigs, The factors related to the spread of disease amongst the farms depended on: the distance to the disease pig farms ( the nearer farms, the higher risk of infection), disinfection ( more than 2 weeks per one disinfection time was higher infection than 1 week per one disinfection time), farm scales (high disease infection rate occurred in small-scale farms, with less than 50 sows), and use of water resource (high disease infection rate in the farms used untreated water). Clinical characteristics of acute diarrhea in piglets were watery diarrhea (100 percent), nausea (90.33 percent), followed by depression, dehydration and rapid death. Common gross lesions of the digestive system in the piglets were the stomach distended, containing curd, undigested food (94.42 percent) and the walls of small intestine were very thin enlarged and contained a lot of water and fluids inside (86.33 percent). Microscopic lesions also occurred in both the stomach and the three sections of the small intestine with the mucous membrane and glands were damaged. These results have contributed to the orientation in the diagnosis of PED and building up measures to limit the spread of PED in pig farms in Vietnam.