Multicentric angiofollicular lymphnode hyperplasia (multicentric Castleman's disease) may be associated with acute phase reaction and several autoimmune features. Since lymphadenopathy is a common feature in connective tissue disease, a clear distinction between the different disease entities may be difficult. We describe a 26-year-old male patient with predominant cervical lymphadenopathy, hepatosplenomegaly and polyserositis, diagnosed as collagen disease. He showed several autoimmune features including autoimmune haemolytic anaemia, cryoglobulinaemia, positive antinuclear and anti smooth muscle antibodies, serum immune complexes and a sensorimotor polyneuropathy. Under immunosuppressive therapy with prednisolone and azathioprine, only partial remission was achieved. Repeated lymph node biopsy together with the clinical features led to the diagnosis of multicentric Castleman's disease in this patient nine years later. Interleukin-6 (IL-6) seems to play an important role in the pathogenesis of clinical and serum biochemical features in patients with Castleman's disease.