Abstract: Objective To understand the differences in epidemiological characteristics of diarrhea between cases reported by the National Notifiable Disease Surveillance System (NNDSS) and those by household surveys in order to provide guidance on the control of the disease. Methods Two household surveys on diarrhea were carried out in Liuzhou City and Luocheng County. Epidemiological characteristics of diarrhea cases reported by the NNDSS and the household surveys were analyzed and compared. Results The incidence rates obtained in the household surveys and the NNDSS were 28870.61/lakh and 203.09/lakh, respectively. A difference of 142.16 times was found. The case fatality rate were 0.00 and 0.30, respectively. The two incidence rates are both observed higher in summer compared with winter. The incidence rate and the health care seeking rate obtained from the household surveys had no significant difference between male and female, while the rate was higher in male than female when analyzing the data collected from the NNDSS. In both data collecting systems, the highest incidence rate was observed in children under 5 years, while the rate was lower in population older than 10 years old. And both rates were highly correlated with the health care seeking rate(r were 0.8516 and 0.8003,respectively, both P＜0.01). More differences in incidence obtained from two systems were found in adults. The most difference was observed in the group of 50-years, which was 677.78 times, while the least difference was in the group of 0-years, which was 21.78 times. For data collected frosm both systems, the highest incidence rates were found in farmers (31.22%)in the household surveys and children cared at home (60.58%)from the NNDSS, respectively. Conclusions The incidence rate obtained in the household surveys was much higher than that from the NNDSS. The incidence rate in infants was closer to the true rate compared with that in adults. For some patients did not seek health care and others were not diagnosed or reported, they were not captured by the NNDSS. It is necessary to strengthen the training of health care providers on the diagnosis principles and to improve the laboratory capacity. The accessibility of the first line health services should be improved so that the health care seeking rate and the effective diagnosis and treatment rate can be improved. This research was funded by Priority Scientific Research Subject of Heath Department of Guangxi Zhuang Autonomous Region (No.200717)