Deregulation of the expression of cytokine genes appears to play a role in the development of gliomas. Interleukin-1 beta has been shown to be synthesized in small amounts by astrocytes and can induce the expression of interleukin-6. Interleukin-6 is not expressed by unstimulated astrocytes, but the deregulation of its expression has been implicated in the progression of several tumor types. In this study, tumor specimens from 16 brain tumors and 22 glioma cell lines were studied for the gene expression of both interleukin-1 beta and interleukin-6, and the coexpression of these two cytokines was found in a significant number of these specimens. The expression of these two growth factor genes may play an important role in the growth and development of human gliomas.