Basic fibroblast growth factor (bFGF) is an established growth factor for melanocytes and a potent angiogenic factor. The expression of bFGF was investigated in 23 desmoplastic melanomas. (DM) (12 males, median age 64 years, and 11 females, median age 54 years) by immunostaining of formalin-fixed, paraffin-embedded sections with high-affinity purified antibody raised against recombinant human bFGF (Scios Nova, Inc.). The tumors were characterized by level II invasion in 1 case (5%), level IV invasion in 11 cases (48%), level V invasion in 8 cases (35%), and indeterminate in 3 cases. bFGF expression was observed in 22 of 23 tumors (95%), either immune localized to tumor cell nuclei in 17 of 22 tumors (77%), or to the cytoplasm of tumor cells in 5 of 22 tumors (23%). Also in these cases, bFGF was strongly expressed in the nuclei of vascular endothelial cells. Maximal expression was noted in the peripheral blood vessels of 20 tumors (91%) versus intratumoral vessels of 13 DM (59%). In conclusion, the expression of predominantly nuclear bFGF by tumor cells in DM suggests a role in mediating the desmoplastic phenotype. In addition, the localization of bFGF to vascular endothelium, particularly at the periphery of the tumor, may be relevant to tumor angiogenesis.