Oral cancer is the most common cancer seen in Papua New Guinea. Although there is a broad geographical correlation with betel chewing, there have been no analytical epidemiological studies and the aetiology remains poorly understood. A greater understanding of several putative risk factors and how they may interact is needed prior to any attempt to modify traditional customs. Although current strategies for primary prevention in India are based on the assumption that the risk of betel chewing is related to the tobacco in the quid, this cannot explain oral cancer in Papua New Guinea. In the latter, special epidemiological and laboratory investigations are needed to provide a scientific basis for future prevention.