PurposePoisoning with elemental metals and metallic compounds was much more frequent in the past, and was related, among other things, to lifestyle and the lack of appropriate toxicological diagnostics. One example is mercury, which is being gradually eliminated but still has many different applications as a pure metal or in the form of various compounds. The paper presents a case of suicidal poisoning with mercury chloride (corrosive sublimate).MethodsForensic and toxicological tests including inductively coupled plasma mass spectrometry (ICP-MS) were at the Department of Forensic Medicine, PMU in Szczecin.ResultsThe patient before death had a range of symptoms such as epigastric pain, vomiting of the stomach contents, central cyanosis with tachycardia, tremors, severe shortness of breath with wheezing, difficulty swallowing, slurred speech, rales in the lungs, and diarrhea. The concentration of mercury measured by ICP-MS was 191 mg/L for a blood sample collected antemortem, and 147 mg/L for a blood sample collected at autopsy. Both concentrations of mercury are regarded as lethal. The post-mortem examination revealed signs of extensive thrombotic necrosis in some internal organs.ConclusionsMercuric chloride has an estimated human fatal dose of between 1 and 4 g. It can produce a range of toxic effects, including corrosive injury, severe gastrointestinal disturbances, acute renal failure, circulatory collapse, and eventual death. The presented case of fatal poisoning with mercury chloride, due to the type of agent used, is now interesting in toxicological practice.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11419-022-00653-7.