Physical illness is a frequent event in everyone's life and in most cases has no particular effect on the psychological structure of the individual. However in the case of serious chronic or disabling illnesses or those occurring at a delicate stage in psychological development, the repercussions may assume social practical, affective and existential dimensions. In its human dimension, illness represents a double existential breakdown, severing links with environment and body that typify a healthy man's existence. This breakdown gives rise to a certain number of painful feelings, mainly of anxiety in acute illness, mainly depressive in chronic illnes, in which the collapse of self-esteem and the compromised self-image appear to be definitive. Such feelings, partly connected directly to the illness and partly caused by the conflicts arising from that condition, in their turn activate a series of mechanisms and defensive behaviour patterns which explain certain incomprehensible attitudes often noted by doctors in their patients and which often hinder treatment.