The effects of dimethyl sulfoxide (DMSO) and dimethylthiourea (DMTU) and deferoxamine (DFO) were investigated in cats during a standard cortical freezing method for the production of vasogenic brain oedema. Hydroxyl radical scavenging activity was studied by electron spin resonance assay using DMPO as the trap. The hydroxyl radical spin adduct was extinguished by DFO and a large dose of DMTU. Evans blue dye extravasation was reduced in DFO and DMSO treated groups as well. DFO appears to be an effective agent for the prevention of cold induced oedema. DMSO and DMTU are direct hydroxyl radical scavengers. These studies suggest that scavenging the hydroxyl radicals has a beneficial effect in the treatment of traumatic brain oedema.