Basic fibroblast growth factor (bFGF) was found to increase the survival of immunocytochemically-identified cholinergic mesopontine neurons in dissociated cell cultures of embryonic rat midbrain. In contrast, cultures exposed to, (a) bFGF and an antibody to bFGF, (b) antibody to bFGF alone, or (c) untreated, contained approximately half the number of cholinergic neurons compared to bFGF-treated cultures.