Transforming growth factor beta (TGF-beta) is involved in the modulation of cell growth, differentiation and repair following injury of various organs. Previous studies on human autopsy material have indicated that TGF-beta isoforms-beta1, -beta2 and -beta3, and TGF-beta receptor type I are expressed in various cells of necrotizing brain lesions like infarction and abscess. The present immunohistochemical study was designed to investigate changes that may occur with regard to TGF-beta and its receptors type I and II in a rat model of focal brain ischemia induced by transient or permanent occlusion of the middle cerebral artery. Our findings indicate that at days 1 and 3 following such transient and permanent ischemia there is an up-regulation of TGF-beta isoforms -beta1, -beta2 and -beta3, and TGF-beta receptor types I and II mainly in the perifocal neurons, reactive astroglial cells, endothelial cells and macrophages.