Cellular immune competence was found to be impaired in previous studies of patients with malignant brain tumors. In patients with nonneural tumors, serum levels of acute-phase proteins were related to immune status and to tumor extent. To determine whether the serum proteins in patients with CNS tumors show similar changes, levels of acute-phase proteins (.alpha.1-acid glycoprotein, .alpha.1-antitrypsin, haptoglobin, C-reactive protein) and immunoglobulins (G, M and A) were assayed in patients with gliomas prior to treatment. Compared to normals, significant increases (P < 0.001) in the acute-phase proteins were found, and the levels were similar to those in patients with nonneural solid neoplasms. Serum immunoglobulins were not significantly increased in patients with gliomas.