Although preclinical studies suggest that methylone (2-methylamino-1-[3,4-methylenedioxyphenyl]propan-1-one) and 5-MeO-MIPT (5-methoxy-N-methyl,N-isopropyl tryptamine) may have psychostimulant properties, the scientific reports about the clinical effects of these agents are scant. We describe a 27-year-old male patient with substance intoxication after a single ingestion of the mixture of methylone and 5-MeO-MIPT. Though he bought the drug as pure methylone powder via an internet order, our chemical analyses indicated that the drug was composed of about 60% methylone (120 mg) and 38% 5-MeO-MIPT (76 mg). This case report suggests that clinicians should be alert to the possibility of the emergence of methylone or 5-MeO-MIPT intoxication, and substance-related mental disorder may be complicated by combined use of other psychoactive drugs.