THE uses and abuses of the principal psychotomimetic drugs have been of increasing interest to mental health workers for approximately the past decade. Numerous articles have dealt with the consequences of ingestion, both in and out of supervised therapeutic settings. The production of prolonged adverse effects, including extended psychotic states, has been of particular significance and concern. Acute psychoses triggered by psychotomimetic drugs frequently run a course indistinguishable from acute psychoses unrelated to drug use. Such druginduced psychotic states are characterized by a relatively well-demarcated onset of the psychosis, and tend to occur in individuals with "poor premorbid" developmental histories. In recent years we have noted increasingly that psychotic patients come to our attention where no clearly defined acute episode can be specified, but who have allegedly used large doses of psychotomimetic substances over extended periods of time. We report here four such cases, in which certain similarities were