Churg-Strauss syndrome is a disseminated vasculitis with multisystem involvement, characterized by necrotizing arteritis, eosinophilic infiltration, and extravascular granuloma formation. In as many as 60% of all cases, the heart may be affected. We describe a 30-year-old man in whom pericarditis was followed by the development of a large pericardial effusion, with evidence of impaired right and left ventricular function. The patient had a 5-year history of asthma. Early therapy with high-dose prednisolone and azathioprine led to resolution of the pericardial effusion and prevented a further reduction in biventricular function.