Aims To evaluate efficacy and safety of intrapericardial treatment with the crystalloid corticosteroid triamcinolone in autoreactive pericardial effusion. Methods and Results Two hundred and sixty consecutive patients with pericarditis/myopericarditis underwent pericardiocentesis, pericardioscopy (Storz-AF 1101B1), and epicardial biopsy with pericardial fluid and tissue analyses. By polymerase chain reaction for cardiotropic viruses/bacteria in pericardial effusion and epicardial biopsies as well as by immunohistochemistry and immunocytochemistry of epicardial and endomyocardial biopsies, 84/260 patients were classified as autoreactive pericarditis and underwent intrapericardial instillation of triamcinolone (group 1: 54 patients, 50% males, mean age 48.9 +/- 14.3 years, triamcinolone 600 mg . m(-2) . 24h(-1) ; group 2: 30 patients, 46.7% males, mean age 52.5 +/- 12.7 years, triamcinolone 300 mg . m(-2) . 24h(-1)). Intrapericardial administration of triamcinolone resulted in symptomatic improvement and prevented effusion recurrence in 92.6% vs 86.7% of the patients after 3 months and in 86.0%, vs 82.1% after 1 year in groups 1 and 2, respectively (P>0.05). There were no treatment-related acute complications. During the follow-up, 29.6% of the patients developed transitory iatrogenic Cushing syndrome in group 1 in contrast to 13.3%,, in group 2 (P<0.05). Conclusion Intrapericardial treatment of autoreactive pericarditis with 300 mg . m(-2) . 24h(-1) of triamcinolone prevented recurrence of symptoms and relapse of effusion as effectively as the 600 mg . m(-2) . 24h(-1) regimen, but with significantly fewer side effects. (C) 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.