In vivo and in vitro expression of lL-6 and its signal transducer genes, IL-6R and gpl30, in human medulloblastoma cells were investigated by the approaches of molecular biology and cellular immunology. The results revealed that 12 out of 13 samples examined were found to express IIMiR and gp 130, but none of them showed IL-6 expression. Then, the potential effects of exogenous IL-6 on the proliferation of medullohlastoma cell line, Med-3 were evaluated, which showed that IL-6 could enhance cell outgrowth dramatically. Our data thus for the first time demonstrate the important role of IL-6 as paracrine growth factor in the proliferation of medulloblastoma cells.