OBJECTIVE: In recent years there has been an increasing interest in the evaluation of the neuronal responses to ischemic insult. Some cytokines, including transforming growth factor-beta 1 (TGF-β1) , are overexpressed after experimental brain demage in animals. This study aimed at the expression of transforming growth factor-betal (TGF-β1) in brain tissue after acute cerebral ischemia in mice. METHODS: Twenty mice were randomly assigned into a normal control group and a cerebral ischemia model group (n = 10 for each). The models of cerebral ischemia were established through ligating the left common carotid artery. The level of TGF-β1 mRNA expression was detected by in situ hybridization. RESULTS: In the model group, the brain tissue presented high levels of TGF-β1 mRNA expression: Grade Ⅲ in 8 cases and Grade Ⅱ in 2 cases, whereas in the normal control group only one case presented Grade Ⅰof TGF-β1 mRNA expression. CONCLUSIONS: TGF-β1 may participate in the pathogenesis of acute cerebral ischemia in mice.