The Workshop on Environmental Exposures and Cancer was held by Cancer Care Ontario (CCO) 25-26 April 2001. An expert panel convened to achieve consensus on a list of important environmental exposures, priority environmental exposures in Ontario, and recommendations for CCO in the areas of surveillance, research, and prevention activities to address these environmental exposures. Panel members developed a working definition of environmental exposure and criteria to prioritize the identified exposures. The process followed in the workshop provided CCO with important direction for its surveillance, research, and prevention activities to address environmental exposures and cancer. It is hoped that the environmental exposures and the opportunities identified through this workshop process will guide policy makers, program personnel, and researchers interested in and struggling with the challenges associated with surveillance, research, and prevention of environmental exposures.