The authors discuss Frances Tustin's work on childhood autism in order to clarify the nature and protective function of autistic barriers in adult patients who present challenging resistances in treatment. Tustin's thesis is that childhood autism constitutes a massive formation of avoidance reactions that develop in infancy to ward off traumatic awareness of bodily separateness. She describes two forms of childhood pathology that may develop: the encapsulated child who defends against all 'not me' experience by means of self-generated bodily sensations that augment the illusion of complete bodily continuity with the mother; and the entangled child who generates a protective illusion of being enfolded inside the body of the mother to minimise the experience of separateness. The transference resistances of borderline adults can be categorised according to Tustin's typology of encapsulation and entanglement. Clinical material is presented from the analyses of two borderline patients, one encapsulated and the other entangled. Despite seemingly different transference manifestations, both belong to the category of autistic barriers inasmuch as they ward off awareness of separation-induced injury to the primal self. The countertransference difficulties that the analyst encounters with patients who employ autistic barriers are discussed and treatment issues are reviewed.