Fibroblast growth factor(FGF) is a mitogen and a potent antigenic factor. It is also known as a differentiation factor for neuroectodermal-derived cell. It has been observed to be expressed in more than 90% of m-RNA of human meningiomas and gliomas. Progesterone receptor(PR) is well known surface receptor of meningioma and its number is greater than that of estrogen receptor. It is one os the known prognostic factors of meningioma. Meningiomas themselves are regarded as benign tumors in general, however some types show aggressive features. In the present study, authors examined the expression of FGF-1 and PR in meningioma tissues using immunohistochemical techniques with monoclonal antibody against human FGF-1 and PR. FGF-1 was detected in 25 of 35 classic meningiomas and in 7 of 9 aggressive ones. PR is expressed in 5 cases of classic and 2 cases of aggressive meningiomas. These results suggest FGF-1 may be involved in aggressive progression of meningioma. There was no significant difference of aggressiveness and expression of FGFR-1 and PR between classic and aggressive meningiomas, including their subtypes.