Abstract-This paper summarizes established multivariate techniques and illustrates examples of their use with ecotoxicological data. Multivariate analysis can be broken down into three main areas of application: ordination, clustering/discrimination, and investigating relationships between sets of variables. Many of these techniques are well established, having been developed in the first half of this century. Although some multivariate techniques predate the very familiar analysis of variance (ANOVA), the popularity of multivariate analysis in ecotoxicology is currently overshadowed by ANOVA and regression techniques. We suggest that this will become increasingly less the case and that we can expect to see much greater use of multivariate techniques in ecotoxicology in the future.