An in vitro epidermal slice technique has been developed for identifying chemicals with the potential to cause a corrosive lesion in animal skin in vivo. Skin-corrosive potential has been correlated with the ability to reduce the skin's penetration barrier by lysis of the stratum corneum. This effect was measured as a lowering of the electrical resistance of an epidermal slice following chemical contact in vitro. An initial validation with 68 chemicals showed the technique to have a high sensitivity for corrosive chemicals. The model has potential as a pre-screen for conventional animal tests and, in contrast to in vivo screening methods, has the advantage of providing quantitative and objective data.