We have followed 45 patients affected with Wegener's granulomatosis and conducted a retrospective analysis of its evolutive aspects and prognostic factors. The study concerned 25 men and 20 women, with an age-range of 50 +/- 15 years at the onset of the disease. The time between occurrence of the first manifestations and the diagnosis was 16 +/- 21 months, the follow-up was 6.3 +/- 8 years. All patients except 3 were given steroids, associated in 39 cases with an immunosuppressor and in 9 cases with plasma exchanges. In 2 localized forms in the ENT area, remission was possible with cotrimoxazole alone. 15 deaths occurred, the causes of which are infection and renal insufficiency when death occurs early, and cardiovascular disorders and neoplasms when death occurs late. The survival probability is 93 p. cent at one year, 83 p. cent at 3 years and 75 p. cent at 5 years from the time of the first manifestations and 75 p. cent at one year, 53 p. cent at 3 years and 50 p. cent at 5 years from the time of the diagnosis. Relapses have been reported in 11 patients, some of which occurred several years after discontinuation of the treatment: they emphasize the need for prolonged monitoring of these patients. Presence of one of the poor prognostic factors: age 50 years (p less than 0.05), presence of renal insufficiency (p less than 0.05) or hemoglobinemia less than or equal to 10 g/cc (p less than 0.05), should be an indication for a more intensive treatment of Wegener's granulomatosis.