The new designer drug 5-(2-aminopropyl)indole (5-IT) is an indole derivative with stimulant properties. Its synthesis was first described by Albert Hofmann and Franz Troxler in 1962. We report four deaths associated with 5-IT and a validated high-performance liquid chromatography method for quantitation of the drug. In all four deaths, an autopsy was performed, and femoral venous blood, heart blood, urine and vitreous humor were submitted for toxicological analysis. The blood specimens were subjected to comprehensive testing that included alcohol analysis by headspace gas chromatography (GC-FID), acidic/neutral, basic drug and opiates screening by liquid chromatography-mass spectrometry (LC-MS-MS), and acidic/neutral, basic and acidic drugs screening by HPLC. In Case 1, a 25-year-old male, 3,4-methylenedioxymethamphetamine (MDMA; 10 mg/L) were detected, and death was attributed to the toxic effects of 5-IT. In Case 2, a 25-year-old female, 3,4-methylenedioxy-N-methylcathinone (methylone, not quantitated), 6-(2-aminopropyl)benzofuran (6-APB; femoral blood 10 mg/L) were detected, and death was attributed to the toxic 'cocktail effects' of the drugs. In Case 3, a 22-year-old male with a history of epilepsy, 5-IT (0.5 mg/L femoral blood) and 6-APB (0.2 mg/L femoral blood) were detected, and death was attributed to the toxic effects of the drugs, with the role of epilepsy being indeterminate. In Case 4, a 25-year-old female, 5-IT (0.4 mg/L femoral blood), amphetamine (0.4 mg/L femoral blood), MDMA (1.5 mg/L femoral blood), 4-methyl-N-ethylcathione, 3,4-methylenedioxyamphetamine HCl (MDA), benzylpiperazine and 6-APB were detected, and death was attributed to the 'cocktail effect' of the drugs.