A workshop on alternative toxicological testing methodologies was convened by the Scientific Group on Methodologies for the Safety Evaluation of Chemicals (SGOMSEC) 26-31 January 1997 in Ispra, Italy, at the European Centre for the Validation of Alternative Methods. The purpose of the workshop was to assess the current status of alternative testing methodologies available to evaluate adverse human health and environmental effects of chemicals. Another objective of the workshop was to identify and recommend research needed to fill knowledge gaps that would lead to new test methodologies. Four work groups were established to address conceptual issues, acute toxicity, organ toxicity, and ecotoxicology. A joint workshop report was prepared for each topic and included recommendations for the development and use of alternative methods. Participants concluded that alternative methods and approaches are available that can be incorporated into tiered strategies for toxicological assessments. Use of these methods will reduce the numbers of animals required, and in some instances reduce animal pain and distress. It was recommended that future efforts to develop test methods should emphasize mechanism-based methods that can provide improved predictions of toxicity. Continued international cooperation was encouraged to facilitate future progress in the development of alternative toxicological testing methods. These methods will provide for improvements in human health protection, environmental protection, and animal welfare.