Within the EU, there is currently much debate about the large number of animals that may be used for experimental testing due to the pending new chemical control system called REACH. One of the main goals of REACH is to close existing toxicity data gaps for EINECS chemicals. Within REACH, there is a provision to use sufficiently validated QSAR models to reduce some of the existing toxicity gaps. Some estimates indicate potential savings of up to one-third of experimental test animals upon average acceptance of alternative models including QSARs. In the current project, the possibilities to develop validated ecotoxicological QSAR models for nitrobenzenes, organophosphates and chlorinated alkanes are explored. In order to extend the number of chemical groups and chemicals that can be covered by QSAR models, the US Environmental Protection Agency ECOSAR Class program is consulted. Existing ECOSAR QSAR models are analyzed and improved where possible. EINECS compounds that fit into the domain of the various QSAR models are defined. Altogether, this results in an estimate of the percentage of EINECS compounds that can be covered by QSAR models.