Psychedelic states occupy a peculiar and contested position within the depth-psychology corpus, functioning simultaneously as pharmacological phenomena, windows onto the unconscious, and occasions for mystical or transpersonal experience. The literature divides, broadly, along three axes. First, the therapeutic tradition — represented most comprehensively by Stanislav Grof — treats psychedelic states as accelerated access routes to perinatal, biographical, and transpersonal strata of the psyche, arguing that high-dose sessions can produce personality transformations of a depth and durability unavailable through conventional analytic work. Second, the neurobiological tradition — most rigorously developed by Carhart-Harris and colleagues — reframes psychedelic states as conditions of elevated neural entropy, in which the default mode network’s ego-sustaining functions are suppressed and primary consciousness re-emerges; this account bridges depth-psychological intuitions about ego dissolution with measurable brain dynamics. Third, the Jungian integration project — notably in Mahr and McGovern — asks whether psychedelic states grant access to archetypal rather than merely personal unconscious material, and whether the clinical and theoretical frameworks of analytical psychology can accommodate, or even require, this expanded phenomenology. Running through all three traditions is the unresolved question of whether the contents disclosed in psychedelic states are ontologically meaningful or artefactual, and whether their therapeutic value depends on mystical interpretation or neurochemical reorganisation alone.