Semistructured interviews were carried out with 20 illicit users of ketamine in Scotland. Participants had used a wide range of illegal drugs. Scottish drug agencies reported limited contact with ketamine users; however, subjects were knowledgeable regarding the licit purpose of ketamine, its effects, and its legal status. Ketamine was usually obtained through diversion from legitimate sources. Three participants reported extensive use, indicating the potential for psychological dependence. A standard dose of ketamine was typically 1/8 g, usually taken intranasally. Participants reported the ketamine experience as being extremely intense and dissociative, usually lasting for approximately one hour. All participants reported using ketamine in a carefully preplanned setting, emphasizing comfort, security, and familiarity. Participants identified potential problems arising from using ketamine in a public place, or in unfamiliar surroundings, and also suggested that novice users may encounter problems through lack of knowledge concerning the intense nature of the experience. Accurate information concerning the effects and nature of ketamine as well as the importance of set and setting should be made available. However, publicizing the drug should be avoided as widespread interest could cause greater problems than currently exist.