Transgenic reporter mice can contribute in the development of less toxic and more selective drugs to treat disease. In this brief communication we describe the generation and initial validation of transgenic mice that provide a visual spatial readout of oxidative stress. These mice carry a LacZ reporter transgene driven by the human haem oxygenase 1 promoter. The induction of LacZ staining by a range of compounds indicated differences in the haem oxygenase 1 spatial response within a tissue. Thus this transgene allows for the spatial monitoring of differences in toxic insult and indicates that this type of transgenic system could have use in toxicity screens.