The concept of precaution has a long history in medicine and public health. The modern precautionary principle (PP), originating from environmental debates in Germany in the 1970s, has been included in many international agreements, such as the Treaty on European Union. PP is a public policy tool that justifies actions, which protect human health and the environment in face of uncertain risks. The outcome of the application of PP depends on the level, nature, and distribution of acceptable risks and on the availability of alternatives, and can range from taking no action to banning of substances or the activities of concern. Given the complex nature and uncertainty of environmental risks to children's health, a precautionary approach is warranted. Public health professionals and clinical practitioners could adopt such an approach within the wider context of considering the environment as a source of risks to children's health. Relevant knowledge and skills are needed to enable health care professionals to address these issues. New methodological and scientific approaches are necessary to make use of scattered, but potentially relevant clinical evidence in providing 'early warnings' of health hazards.