Methoxetamine (MXE) is a psychoactive substance distributed mostly via the Internet and is not liable to legal regulation in Poland. MXE has a toxicity profile similar to that of ketamine but longer-lasting effects. The paper describes a case of acute poisoning that resulted from recreational use of MXE and amphetamine and ended in death. In mid-July 2012, a 31-year old man was admitted to the clinical toxicology unit in Gdańsk because of poisoning with an unknown psychoactive substance. The patient was transported to the emergency department (ED) at 5:15 a.m. in a very poor general condition, in a deep coma, with acute respiratory failure, hyperthermia (> 39°C) and generalized seizures. Laboratory tests showed marked leukocytosis, signs of massive rhabdomyolysis, hepatic failure and beginning of acute renal failure. Despite intensive therapy, the patient died 4 weeks after the poisoning in the course of multi-organ dysfunction syndrome. Chemical and toxicological studies of serum and urine samples collected on the poisoning day at 1:40 p.m. confirmed that amphetamine and MXE had been taken earlier that day. Concentration of amphetamine in the serum (0.06 μg/ml) was within the non-toxic range, while MXE (0.32 μg/ml) was within the toxic range of concentrations. Amphetamine was also detected in the patient’s hair, which suggested a possibility of its use within the last dozen weeks or so. The serious clinical course of intoxication and co-existence of amphetamine and MXE in the patient’s blood and urine suggest the possibility of adverse interactions between them.