Introduction: Infliction of harm to life and health due to medical errors is common for the whole world and post-Soviet countries, in particular. The problem of these errors is one of the most important in medical law, although there is no unified concept of it. A small number of sentences in cases of criminal negligence of medical professionals indicates a high latency and often unprovability of this crime in a number of post-Soviet countries. The aim: To disclose the objective and subjective prerequisites of a medical error, reasons for its occurrence, to establish the grounds for criminal liability of medical professionals in case they commit an error and to examine the judicial practice in this regard. Also, to define the concept and types of circumstances exempting criminal liability and their impact on criminal liability issues concerning medical professionals. Materials and methods: The study is based on the Belarusian, Kazakh, Moldavian and Ukrainian statutory acts as well as international acts, the European Convention for the Protection of Human Rights and Fundamental Freedoms, case law of the European Court of Human Rights (ECHR), national court judgments. Such methods as dialectical, comparative, analytic, synthetic and comprehensive have been used in the paper. Review: On the basis of the study, it has been established that there is no unified concept of a medical error, medical personnel are fairly brought to criminal liability only if they commit an unjustifiable error in the presence of all the mandatory elements of a crime provided for in the relevant article of the Criminal Code. At the same time, it is extremely difficult to prove existence of such an error. Besides, at the state levels, causes and mechanisms of occurring errors have not been revealed, they are not even discussed, which makes it impossible to outline measures to prevent them or reduce their frequency and degree of danger. Conclusions: The struggle against medical errors should encompass a number of such activities as standardization of clinical treatment protocols, further education of medical professionals and lawyers in regard to patient safety, thorough investigation of each incident in order to exclude a justifiable error or circumstances exempting criminal liability. Equitable, severe and uncompromising punishments for perpetrators should be an effective means preventing commission of crimes in medicine.