The aim of this article was to present, often challenging, clinical cases with suspected intoxication/poisoning. The veterinarian is often the first one who contacts these cases. In the conduct of investigation to determine the causative agent, a number of difficulties may occur which are connected with the specificity of veterinary toxicology. In recent years there have been reported numerous cases related to crime – intentional poisoning which causes pain, severe suffering and eventually death. According to Polish law about animal protection (1997), such cases should be reported to the police and then subjected to official proceedings. Determining the cause of poisoning is often a long-lasting process that requires specific treatment. An important element of toxicological diagnostics is the insight in fact-finding at all stages of the veterinary-medical procedure during extensive interviews, detailed description of clinical symptoms and/or sections, the appropriate collection and preservation of laboratory samples. The goal of the publication is to show the problems encountered by veterinarian in the toxicological procedures, to indicate the proper course of the procedure and the most frequently committed inconsistencies, so as to avoid them.