To investigate the age-standardized incidence, demography, recent trends and patterns of incidence of oral cancer in Sri Lanka between 1985 and 2005. Data on oral and oropharyngeal cancers were obtained from the published hospital-based cancer registry reports in the years 1985, 1990, 1995, 2000, and 2005. The data were analyzed by gender, age (<40 or >40 years), and by site. A linear regression analysis was performed on the age-standardized oral and oropharyngeal cancer incidence rates to examine the trends over a 20-year period. There was a steady decline in the age-standardized incidence of lip and oral cavity cancers over the past 20 years in both men and women. A significant reduction of 1.9% per year is noted over this period. Contrary to this, cancers of the oropharynx (C09, C10, and C14) showed a slight increase over the same period. Reversal of betel quid use and smoking must be considered in accounting for declining trends for oral cancer. Increasing rates of oropharyngeal cancer raises the issue whether risk factors for the oropharynx are different to those of the oral cavity, and this may need further investigation.