Abstract: Objective To understand the incidence pattern and etiological characteristics of acute diarrhea in Pudong New Area, Shanghai and provide evidence for the prevention and control of acute diarrhea. Methods Clinical samples were collected in 12 sentinel hospitals in Pudong in 2012 to detect 8 bacterial pathogens and 5 viral pathogens. Results From January to December 2012,clinical samples were collected from 2533 acute diarrhea cases in the sentinel hospitals. Among these cases, 498 were infected with one bacterial pathogen (19.66%) and 561 bacterial strains of were isolated, including 156 diarrheagenic Escherichiacoli coli (E. coli)strains (27.81%),120 Salmonella strains (21.39%) and 101 Aeromonasstrains (18.00%), and 716 were infected with one viral pathogen (28.31%) and 756 viral strains were isolated, including 472 norovirus strains (65.83%) and 164 rotavirus strains (21.69%). The detection rate was high for bacteria during June-September and for viruses during January-March and during October-December. The detection rate of viruses was significantly higher than that of bacteria in any population (P0.001). The detection rate was obvious higher in adults than in children. Conclusion Acute diarrhea were mainly caused by viruses in Pudong, but the incidence of bacterial infection was still high. The incidence peaks of two type infections were different. The major pathogens causing bacterial infections were E. coli, Salmonella and Aeromonasand the major pathogens causing viral infections were norovirus and rotavirus. The pathogen spectrums of acute diarrhea in adults and children were different.