That experiences which occur during a hypnoid or infantile state are later unrecallable dates back in the psychoanalytic literature to Breuer. The present study attempts to evaluate the modifications in recall that follow the altered state of consciousness produced by LSD-25. The subjects completed an extensive questionnaire before, during, and a day after the drug was given. The aspects of the drug reaction that were best recalled represented those experiences that were most concrete, easily identified, and likely to have occurred in normal states of consciousness. Those most poorly recalled included feelings of extreme passivity, feelings of loss of control, and experiences that seemed to reflect a weakening of ego boundaries with a loss of sense of self.