In this Grand Round we present a 32-yr-old African man who became severely ill after a 5-month history of weight loss, pyrexia, arthralgia, sweats and rash. He went on to develop pericarditis, pericardial effusion with tamponade, hepatomegaly with abnormal liver function tests, lymphadenopathy, massive proteinuria and required ventilatory, circulatory and renal support. The differential diagnosis was adult onset Still's disease, systemic lupus erythematosus (SLE), infection and lymphoma. Primary infection and lymphoma were excluded and he was treated, with dramatic success, with intravenous immunoglobulins (i.v.IG). Subsequent renal biopsy excluded SLE but confirmed collapsing glomerulopathy. The proteinuria improved dramatically following treatment with mycophenolate mofetil. We discuss some of the difficult diagnostic and management issues raised by this patient and the different uses and mechanisms of action of i.v.IG.