BACKGROUND Sixty-three patients with generalized pustular psoriasis were hospitalized during a 29-year period. They were classified into four subgroups on the basis of onset and morphologic pattern of disease: acute (von Zumbusch), subacute annular, chronic (acral), and mixed. This division provides a better understanding of the variability of the disease and helps in choosing treatment. METHODS The average age at onset was 50 years; male and female patients were affected about equally. In 11 patients, flares were precipitated by localized infections. Approximately one fourth of the patients had complications; most were superinfections. The average stay in the hospital was 30 days; factors correlating with a long hospitalization were hypocalcemia, female sex, and a previous history of psoriasis vulgaris or pustular psoriasis. CONCLUSIONS Whereas topical therapy was helpful, systemic medications were often needed. Coal tar, ultraviolet light, and psoralen-ultraviolet A may be effective; however, they must be used with caution, because they may exacerbate the disease.