Carfentanyl, an ultra-potent synthetic opioid, is approved for use only in veterinary medicine as a tranquilizing agent. However, many cases of human poisoning with carfentanyl have recently appeared in the news with limited information given and scientific literature provides only 1 case of documented human exposure to carfentanyl.Fifteen cases of death from drug overdoses with carfentanyl involvement are being presented. Fifteen blood and urine samples have been taken for alcohol and drug testing. Headspace gas chromatography was used for alcohol detection. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and liquid chromatography–time-of-flight mass spectrometry (LC/MS TOF) system was used for drug detection.Sixty-three cases of death from poisoning with drugs have been tested for carfentanyl in the State Forensic Medicine Service. Fifteen of them were positive for carfentanyl.The cases mentioned above show that carfentanyl exposure causes signs and symptoms similar to other opioid toxicity. Carfentanyl intoxication may even be fatal if appropriate treatment is not available. Therefore, nowadays it is very important to draw forensic medicine expert's attention to new substances in drug trade.