The development of the concept of the Negative Therapeutic Reaction (N.T.R.) is followed through from the original description by Freud to that of later and contemporary psychoanalysts, revealing a considerable divergence of opinions as to the causes of the condition. It is suggested that in the more chronic forms the reaction is a special kind of acting out of the transference in the psychoanalytic situation, when it is also a particularly stubborn defence against the re-experiencing of pain and psychic suffering associated with early trauma. It is generally agreed that the N.T.R. is a challenge to the analyst's countertransference. On the other hand, it is also of positive value as an indicatior of the state of the transference and the possibility that an especially painful area in the patient's psychopathology has been reached, requiring a further working through and better integration. Two clinical illustrations are presented in support of these theoretical considerations.