2-Methyl-AP-237 HCl is the hydrochloride salt form of 2-Methyl-AP-237, a synthetic opioid-related compound that has attracted attention in analytical, forensic, toxicological, and novel psychoactive substance (NPS) research. Because its scientific history is considerably less extensive than that of established pharmaceutical opioids, researchers should approach available information with appropriate caution and distinguish experimentally established findings from assumptions based on structurally related compounds.