In overviews concerning environmental cancers, the definition of 'environmental' can vary considerably in terms of the list of exposures considered, due to differences in inclusion criteria, and the articles tend to focus mainly or exclusively on Western populations. International agencies such as World Health Organisation, that have had considerable success in fighting infectious diseases, seem to be weaker when considering the relevance of environmental carcinogens, particularly in developing countries, and in identifying the exposed populations. The purpose of this paper is to reexamine the issue with a specific focus on developing countries. There are good reasons to believe that the burden of environmental cancers in such countries is high and has been underestimated in previous analyses. We examine the most common pollutants (aflatoxins, arsenic, air pollutants, biomass fuel and coal, polychlorinated biphenyls and wastes). A systematic review was not possible given the sparse nature of the data, but we suggest that the burden of environmental exposures to carcinogens can be substantial in developing countries.