Generalized pustular psoriasis shows a fluctuating pattern, its course varying with time and from patient to patient. The prognosis and results of treatment are therefore extremely difficult to assess. The patients in this series have been followed up by us with regard to the natural course of the illness including complications and precipitating factors. Oral drug therapy has suprisingly often provoked acute pustular eruptions, and these patients have also strikingly often and rapidly developed contact allergy to topical applications. The undesirable effects of long-term systemic corticosteroid therapy have been confirmed in this series, chiefly by severe rebound phenomena, notwithstanding that such treatment has proved the only means of rapidly reversing life-threatening states. The effects of methotrexate and hydroxyurea were at times good but, not uncommonly, mediocre and occasionally even useless. Large doses of antibiotics have also failed to achieve the results described by others. On the contrary, secondary infection with beta-hemolytic streptococci has caused serious problems in several cases. Apart from careful protection from infection and precipitating factors, little can be done to influence the course of generalized pustular psoriasis, but trial with cytostatics is justified during severe bouts, pending the appearance of new lines of therapy.