The distribution of mephedrone in the body fluids and tissues of a subject found dead after the concomitant intake of cocaine and mephedrone is reported. Mephedrone (4-methylmethcathinone) is a designer drug of the phenethylamine family that is able to cause central nervous system stimulation, psychoactivity and hallucinations and that is becoming popular among youth as a recreational drug. Mephedrone has been available in Europe since 2007, and it is sold through the internet and by local shops as bath salt or plant food. In the case reported here, a 25-year-old man was found dead in the apartment of a friend after a night spent in several local clubs. A fragment of a blue diamond-shaped pill was found in the pocket of the trousers worn by the decedent. During the autopsy, no evidence of natural disease or trauma was found to account for this death. Blood, urine and gastric content samples were collected and submitted for toxicological analysis. Moreover, bile, brain, lung and hair samples were collected as additional matrices. The content of the pill was submitted to a general screening analysis in order to determine its composition. Mephedrone was detected in the blood, urine, gastric contents and in the additional matrices using an expressly validated GC/MS method. The blood and urine concentrations were 1.33mg/L and 144mg/L, respectively. Contextually, cocaine and cocaethylene were found in the blood and urine specimens. The distribution of mephedrone in the body organs was evaluated by analyzing the brain, bile and lung specimens. Hair analysis revealed a past exposure to mephedrone, ketamine, MDMA and cocaine. Sildenafil was identified as the main component of the blue, diamond-shaped pill. The quantitative determination of mephedrone in several body fluids and tissues provides significant knowledge about the distribution of this new drug of abuse in the human body after massive ingestion.