Smoking and betel quid chewing are established risk factors for oral cancer in Taiwan. The prevalence of these risk factors in the central county of Changhua falls within the middle range nationally, yet the county has the highest incidence of oral cancer in Taiwan. The purpose of this study, therefore, was to identify if patients' ages and prognoses at diagnosis were related to their place of residence and, if so, to explore environmental and geographical factors which might explain local variance in the incidence of oral cancers within Changhua and their prevalence in the county as a whole. The paper contains results from a retrospective review of medical records for patients diagnosed with oral cancer in Changhua County who were treated at the Changhua Christian Hospital (CCH) between 1994 and 2005. The Wilcoxon signed rank test, ANOVA, t-test, Kaplan-Meier curve and log-rank tests were carried out to examine the association between patients' places of residence, their ages at diagnosis, and their overall prognoses. A total of 1363 oral cancer cases were diagnosed in the study period. These consisted of 1272 males and 91 females. A steady increase in the number of patients diagnosed with oral cancer annually was noted. The tongue and buccal mucosa were the two most frequently affected sites constituting 56% of cases, while squamous cell carcinoma was diagnosed in nearly 80% of the study population. The mean ages at diagnosis were 53.1 and 52.8 years for patients living in the northern and central areas of Changhua, and 55.1 years for those living in the south. Patients living in the northern and central areas of Changhua had poorer long-term prognoses as indicated by Kaplan-Meier survival curves and the log-rank test, and it appears that differences in the level, type and distribution of industry in these areas distinguish these patients from those living in the south of the county. In particular, the density of electroplating factories in northern and central Changhua is significantly higher than in the south. Patients living in northern and central areas of Changhua have their oral cancers diagnosed at a younger age and have poorer long-term prognoses than those living in the south of the county in spite of their being treated at the same hospital. We conclude that factors explaining local differences in the prognosis of oral cancer patients in this part of Taiwan require further investigation, as does Changhua's high overall incidence for these cancers.