The article describes one of the most urgent needs of the investigation the development of a fundamentally new approach to the forensic medical assessment of harm to human health caused by environmental crimes. Th e special signifi cance of new approaches to establishing a causal relationship between a committed environmental off ense and harm to life and (or) health, including for distinguishing from other possible anthropogenic impacts, is shown. A practical example of expert assistance to the investigation in establishing the circumstances to be proved during the investigation of an environmental crime is given.