In the hope that an uncommon view of a common disease might afford new insight, we have closely observed 2 cases of psoriasis in the rare acute pustular phase. We believe that in such generalized pustular psoriasis one can see an enormous magnification, acceleration, and accentuation of what otherwise is a slow, insidious, chronic scaling process. Our observations underscore the belief that the leukocytes must play a significant role in the pathogenesis of this disease, both in its classical micropustular and in its rare macropustular form. Report of Cases Case 1.— One week prior to hospital admission, this 58-year-old woman had developed an acute exacerbation of her long-standing psoriasis. She had had recalcitrant generalized psoriasis for over 16 years, requiring hospitalization on 3 previous occasions. The present attack began as erythematosquamous lesions of her arms and legs. It rapidly spread within a day to involve the chest and back. On examination