Abstract: The research compound 25I-NBOMe, also known as CIMBI-5 or INBMeO, was created in academic laboratories as a potent serotonin 2A receptor agonist. Because of its high affinity and ambiguous legal status, recreational drug enthusiasts have used this compound as a powerful alternative to other hallucinogenic drugs such as lysergic acid diethylamide. We report 2 deaths after 25I-NBOMe ingestion by decedents who attended separate “rave” parties. The first case involved a 21-year-old male who admitted taking “acid” to his friend. A sudden violent rage caused him to flail about, and he subsequently became unresponsive. The postmortem examination revealed numerous external injuries that were consistent with physical aggression. The second case involved a 15-year-old female who was socializing outside a rave party, became ill, and rapidly deteriorated as her friend transported her to the hospital. The postmortem assessment was similar to the first case in that external contusions featured prominently. Comprehensive toxicology screens in both cases revealed only evidence of marijuana use. A deeper analysis using time-of-flight mass spectrometry revealed the presence of 25I-NBOMe, which was further confirmed by tandem-mass spectrometry. The behavior and injuries in these cases reveal a consistent pattern preceding fatal 25I-NBOMe toxicity.