We tested by radioimmunoassay the sera of 22,707 male Chinese government employees in Taiwan for HBsAg and found 15.2% to be positive. Almost all were confirmed as carriers by follow-up testing 1 year later. This paper presents HBsAg positivity rates of these men according to the province of China from which they originated, and compares the rates with published provincial mortality rates for primary hepatocellular carcinoma. Moderate variation in carrier rates between provinces was observed with high prevalence in men from provinces south of the Yangtze River. There was positive correlation between HBsAg prevalence and primary hepatocellular carcinoma incidence giving further support to the possibility of a causal relationship.