Summary This report has presented 20 further hypnotic experiments in symptom substitution. The results of these experiments have tended to support the findings and conclusions of a previous investigation employing this method: that psychodynamically equivalent symptoms may replace original conversion reactions, but nonequivalent symptoms cannot be substituted in this way. The concept of "psychodynamic equivalence" of symptoms has been revised and expanded to include relationships in terms of regressive depth (vertical equivalence) as well as correlations based upon similarity in symbolic expression (horizontal equivalence). The following symptom substitutions were induced in the present experiments: Hysterical tremor of the hands and forearms were replaced by torticollis, gagging-choking-vomiting, headache, and dissociated acting out of an impulse to strangle. Bulimia was replaced by finger-biting, depression, vomiting, pruritus and excoriation, herpes zoster, paresis of the right arm, pain and paralysis of the leg, pleuritis (?), urticaria, paranoid phantasies, phobias, headache, insomnia, pedophilia, eczematous dermatitis of the face, disrobing compulsion, unconsciously motivated "accidental" self-injury, and bronchopneumonia (?). Pedophilia was replaced by an obsessive preoccupation with thoughts of injuring a child. Headache was replaced by pruritus and excoriation, abdominal pain with nausea and vomiting, numbness and paresthesias of the forearm and hand, facial hemiparesis, and "burning" pain of the forearm. Numbness of the right fifth finger was replaced by numbness of an entire hand, wrist, and forearm, and by nausea and vomiting. Other observations and hypotheses which arose from the present investigation were: This experimental method for investigating the psychodynamics, psycho-economics, and symbolism of symptom formation involves certain dangers which must be anticipated and controlled. The principal complication to be avoided is hypnotic removal of hysterical symptoms which defend against potentially psychotic dissociative reactions. Hypnotically induced substitute symptoms for original conversion reactions tend to draw upon the patient‘s previous repertoire of symptoms. Novel replacement symptoms tend to occur only if previous symptoms are hypnotically interdicted. Some findings of the present investigation support Kepec's hypothesis that shifts of symptoms into the head and to the body surface indicate that ego-alien impulses and feelings are nearing awareness and overt expression. Vegetative neurotic symptoms may replace conversion reactions. When this occurs, the vegetative symptom often appears to subserve symbolic functions similar to the conversion reaction which it replaces. The symbolism of vegetative neurotic symptoms is seldom, if ever, as specific ideationally as that of conversion reactions. Hypnotically suggested replacement symptoms which are foreign to the patient's psychology tend to be unsuccessful substitutes. Serial substitution of several replacement symptoms for a single conversion reaction results in a sequence of symptom formations, the order of development of which can be investigated by this experimental method, and can be explained in psychodynamic and psycho-economic terms. Hypnotic removal of organic pain is not followed by the development of substitute symptoms, unless the organic pain is secondarily invested with a masochistic psychoeconomic function. Psychogenic symptoms, despite their biological uselessness, are valued by the unconscious as indispensable allies. Organic symptoms, despite their biological usefulness as warning signals, are reacted to as "irritants," which the unconscious wishes to get rid of or extinguish. Under certain circumstances, paranoia may represent a dynamic equivalent of depression. Current theories which may account for this phenomenon are the concepts of Bak, according- to which paranoia is formulated as "delusional masochism," and the concepts of Melanie Klein concerning regressions to depressive and paranoid positions of fixation. The choice of substitute symptoms is influenced not merely by endopsychic, but also by current environmental factors. Symptomatic. regression never consists purely of fixated infantile activities or constructions, but always carries with it elements of the current conflict which gave rise to the regression. Hypnotic suggestion that more mature methods for solving conflicts will develop may induce a change in depth of regressive symptomatic defense, such as a shift upwards psychosexually from oral to phallic regressive defense. Some findings of the present experiments suggest that infectious diseases may occur as substitute reactions for hypnotically removed psychogenic symptoms. Conversion symptoms appear to employ the same type of "economy" by condensation which characterizes symbolism in dreams.