This is a detailed report of two cases of ulcerative colitis, studied psychoanalytically, which showed genetic and dynamic similarities. The struggle with anxiety and rage was prominent from early childhood. Mature, adaptive behavior yielded to infantile dependency in the pursuit of security and gratification. Threats to self-esteem precipitated attacks of colitis three or four weeks later. The loss of successful mastery coincided with depression, somatic symptoms, and overwhelming anxiety and rage. The meaning of the physical symptoms accompanied by regressive phenomena is elaborated; certain sexual deviations of these patients are also discussed. The authors believe that it is easier to speak of the perpetuating psychological mechanisms of such an illness as this than of the initiating ones. They are aware that the relation between the psychological and physiological remains a problem. The psychological mechanisms suggest that this is a disintegrative illness; physiological research should be pursued with this fact in mind.