Twelve patients with brain tumors and progressive edema caused by tumor progression or radiochemotherapy-related leukoencephalopathy were treated with H15, a phytotherapeutic anti-inflammatory agent. Edema was reduced in two of seven patients with glioblastoma with tumor progression and in three of five patients with treatment-related leukoencephalopathy. All patients with leukoencephalopathy improved clinically for several months.