Objective To investigate the cause and to find out the food and the agent responsible for the outbreak,the defects in handling foods,and to make recommendations for the prevention of food poisoning.Methods A case-control method was used to collect vomitus and stool samples from poisoning cases and suspected leftover foods for testing 12 types of enteric pathogens.Results There were 42 poisoning cases from 270 people sharing the same foods in a party.The symptoms were stomachache in 100%,diarrhea in 85%,nausea in 63%,vomiting in 58% and fever in 40% of poisoning cases.The incubation period of illness was 6 to 57 h(median:25 h) after having foods.A kind of sliced boiled chicken dish has been consumed by 87%(34/39) of case-guests and by 53%(32/60) of control-guests(OR =6.0,95% CI:2.0～17).The OR increased with the amount of chicken consumed(χ2trend=4.5,P=0.03).Aeromonas hydrophila was detected from the leftover chicken and a stool sample.No other enteric pathogens were detected.Conclusion Aeromonas hydrophila in sliced boiled chicken was the main cause responsible for the outbreak of food poisoning.It is recommended to enhance training qualified cooks and kitchen workers to make sure that they have a good knowledge on food processing and preservation.