A 13-year-old boy with an anaplastic meningioma at the site of the jugular foramen had an increased serum level of aklaline phosphatase (ALPase) (liver form) in the serum before surgery. Immediately after excision of the tumor, the serum ALPase level decreased dramatically. Histochemical and immunohistochemical examinations revealed ALPase activity (liver form) in the neoplastic cells. This case would be the third with clinical evidence that the increased level of serum ALPase is of neoplastic cell origin from the meningioma. The implications of ALPase in brain tumors are discussed.