Basic fibroblast growth factor (bFGF) is a heparin-binding protein implicated in the differentiation, proliferation, and maintenance of cells in the central and peripheral nervous systems. Methods for modulating bFGF expression would, therefore, be useful for examining the function(s) of bFGF in neural tissue. Here we evaluate the effects of bFGF-specific antisense oligonucleotides on bFGF expression in two distinct cell culture systems. The first culture system employed an established human glioma cell line expressing hl~h levels of bFGF protein. Inhibition of bFGF expression in this system by antisense oligonucleotides inhibited bFGFs mitogenic effects. The second system utilized primary cultures derived from peripheral nerve explants. in these cultures, neural crest-derived melanocyte/Schwann cell progenitors from peripheral nerve undergo a transformation into melanocytes in response to treatment with bFGF or phorbol esters. Antisense primers directed to two different sites of bFGF mRNA suppressed this phorbol este-rinduced melanogenesis in peripheral nerve explants in a saturable and specific manner. Sense strand primers or sequence-scrambled antisense primers were ineffective in this regard. Western blot and immunocytochemical analyses demonstrated that only antisense primers significantly reduced the specific activity of bFGF protein in glioma cell or phorbol ester-treated peripheral nerve culture extracts, confirming that these antisense oligonucleotides interfered with bFGF protein expression.The application of FGF-specific antisense primers should prove useful in elucidating the role of FGF family members in nervous system development and maintenance.