Objectives: To estimate the proportion of liver cancer cases and deaths due to infection with hepatitis B virus(HBV), hepatitis C virus (HCV), aflatoxin exposure, alcohol drinking and smoking in China in 2005. Studydesign: Systemic assessment of the burden of five modifiable risk factors on the occurrence of liver cancer inChina using the population attributable fraction. Methods: We estimated the population attributable fractionof liver cancer caused by five modifiable risk factors using the prevalence data around 1990 and data on relativerisks from meta-analyses, and large-scale observational studies. Liver cancer mortality data were from the 3rdNational Death Causes Survey, and data on liver cancer incidence were estimated from the mortality data fromcancer registries in China and a mortality/incidence ratio calculated. Results: We estimated that HBV infectionwas responsible for 65.9% of liver cancer deaths in men and 58.4% in women, while HCV was responsible for27.3% and 28.6% respectively. The fraction of liver cancer deaths attributable to aflatoxin was estimated to be25.0% for both men and women. Alcohol drinking was responsible for 23.4% of liver cancer deaths in men and2.2% in women. Smoking was responsible for 18.7% and 1.0% . Overall, 86% of liver cancer mortality andincidence (88% in men and 78% in women) was attributable to these five modifiable risk factors. Conclusions:HBV, HCV, aflatoxin, alcohol drinking and tobacco smoking were responsible for 86% of liver cancer mortalityand incidence in China in 2005. Our findings provide useful data for developing guidelines for liver cancerprevention and control in China and other developing countries.