The case histories of the 49 patients who died in a series of 165 patients admitted to the Medical Unit between 1958 and 1984 with polyarteritis nodosa (PAN) were reviewed. The causes of death of the 29 men and 20 women, mean age 51.44 +/- 7.4 years, were classified into 6 groups. Infection accounted for 26.5% (13/49) of deaths, the initial site of infection being pulmonary, complicated by septicaemia in 6 cases. Cardiovascular events were responsible for death in 24.4% (11/49): terminal cardiac failure (4 cases), myocardial infarction (1 case), ventricular tachycardia (1 case), stroke (1 case), pulmonary embolism (2 cases), fulminant hemoptysis (1 case). Gastrointestinal complications were the cause of death in 16.3% (8/49): ischemic necrosis (5 cases), acute pancreatitis (2 cases), oesophageal ulceration (1 case). Renal failure was observed in 10.2% (5/49), all occurring before 1972: acute renal failure (3 cases), chronic renal failure (2 cases). Cancer was the cause of death in 10.2% (5/49): primary bronchial carcinoma (2 cases), laryngeal carcinoma (1 case), carcinoma of the vulva (1 case), bone metastases (1 case). Finally, 14.2% (7/49) could not be classified in the preceding groups. Sudden death occurred in 3 patients, shock in 1 patient, multivisceral PAN in 2 patients and anaphylactic shock in 1 patient. Three of the 12 patients who had post-mortem studies had signs of progressive vasculitis. The results are compared with other reports in the literature and the pathogenic mechanisms are discussed. The infections and cardiovascular deaths occurred early or late and were not related to the state of the activity of the vasculitis. Immunosuppressive treatment seems to play an important role in their pathogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)