Cerebral edema produced by brain tumors is clinically and experimentally reduced by steroid therapy. Nonsteroid anti-inflammatory drugs (NSAID's) which have been used to treat non-neural inflammation and swelling have not been evaluated for their ability to affect edema produced by brain tumors. The authors have used the rat C6 glioma spheroid implantation model to compare the effects of two steroids (dexamethasone and methylprednisolone) and two NSAID's (ibuprofen and indomethacin) on protein extravasation caused by intracranial gliomas. Evans blue dye was used as a marker for serum albumin extravasation. The concentration of Evans blue dye was measured in the tumor and peritumoral and contralateral brain tissue 1 hour after intravenous injection. Extravasation of Evans blue dye within the tumor was decreased in all treatment groups when compared to placebo-injected control animals. The differences between the control specimens and those treated with dexamethasone, methylprednisolone, and indomethacin were highly significant (p less than ). The Evans blue staining was also decreased in the peritumoral and contralateral brain. These results indicate that NSAID's compare favorably with steroids in diminishing tumor-induced protein extravasation. It is suggested that NSAID's may prove to be beneficial in clinical instances used either in conjunction with steroid therapy or alone when steroids are contraindicated.