The European Centre for the Validation of Alternative Methods (ECVAM) has supported validation studies on in vitro tests for skin corrosion, resulting in the validities of four alternative tests being endorsed. The US Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) has also evaluated the validity of these alternative methods for skin corrosion testing. In the European Union, a new Test Method on Skin Corrosion (B.40), incorporating the rat skin transcutaneous electrical resistance and human skin model assays, was included in Annex V of Directive 67/548/EEC in mid-2000. At an international level, two OECD Test Guidelines (430 and 431) on these alternative methods have been approved as of May 2002. To date, there are no validated in vitro tests for predicting the dermal irritancy of chemicals. ECVAM supported prevalidation studies on five in vitro tests for acute skin irritation during 1999-2001. These tests were based on human, pig and mouse skin. However, none of them met the criteria set for inclusion in a large-scale formal validation study. Following additional work on the test protocols and/or prediction models, it appears that several modified tests could now be ready for validation in 2003.