Abstract: Objective To examine the risk factors of Giardia Lamblia infection in the residents at both sides of China Myanmar border area in Nabang port of Yunnan province.Methods An epidemiological survey was carried out with clustered random sampling in the border villages of Nabang township of China and Laiza city of Myanmar in 2008.The data and fecal samples were collected from the villagers who living in the sampled villages more than one year.The fecal samples with iodine staining were examined with microscopy.The data were analyzed with univariate and multivariate non-conditional logistic regression.Results Totally 903 residents from 6 villages were investigated and 13 kinds of risk factors were analyzed.The average age of the residents was 22.81±18.82 years and the overall infection rate of Giardia Lamblia was 13.51%.Among the residents,there were 286 infected Chinese with a infection rate of 2.10% and 617 infected Burmese with a infection rate of 18.8%.The results of univariate non-conditional logistic analysis showed that the risk factors of the infection were nationality,age group,race,eating with hand,drinking unboiled water,the source of drinking water,diarrhea during last month,the type of lavatory used,and with mucous fecal.The results of multivariate non-conditional logistic analysis showed that the main risk factors were nationality,age group,race,drinking unboiled water,and with mucous fecal.Conclusion The main reason of high prevalence of Giardia Lamblia infection in Burmese villages is drinking unboiled water polluted by fecal.