Due to uncontrolled use for several decades, dichlorodiphenyltrichloroethane (DDT), probably the best known and most useful insecticide in the world, has damaged wildlife and might have negative effects on human health. This review gives a brief history of the use of DDT in various countries and presents the results of epidemiologic and experimental studies of carcinogenesis. Even though its use has been prohibited in most countries for ecologic considerations, mainly because of its negative impact on wildlife, it is still used in some developing countries for essential public health purposes, and it is still produced for export in at least three countries. Due to its stability and its capacity to accumulate in adipose tissue, it is found in human tissues, and there is now not a single living organism on the planet that does not contain DDT. The possible contribution of DDT to increasing the risks for cancers at various sites and its possible role as an endocrine disruptor deserve further investigation. Although there is convincing experimental evidence for the carcinogenicity of DDT and of its main metabolites DDE and DDD, epidemiologic studies have provided contrasting or inconclusive, although prevailingly negative, results. The presence and persistence of DDT and its metabolites worldwide are still problems of great relevance to public health. Efficient pesticides that do not have the negative properties of DDT, together with the development of alternative methods to fight malaria, should be sought with the goal of completely banning DDT.