Keywords: 
• QSAR /
• acute aquatic toxicity /
• mode of action

Abstract: Chemical contaminations lead potential risks to both human health and ecological environment. However, the lack of available data on the hazardous properties of chemicals is the major challenge for the risk assessment of chemicals. Non-animal alternative methods are encouraged to fill in data gaps by OECD and US EPA. Quantitative structure-activity relationship (QSAR) approach is regarded as one promising alternative technique. Information on acute toxicity to aquatic organisms are commonly used in the risk assessment and screening of priority substances. But, the available experimental toxicity data are very limited currently. In this paper, three types of prediction models of acute toxicity are summarized, including (1) models for particular chemical classes; (2) statistically derived models that are developed without an a priority mechanistic hypothe-sis; (3) models for a given mode or mechanism of action (MOA). The predictive ability, applicability domain and mechanism interpretation of the three type models are compared. QSAR models based on MOA, which generally demonstrate rather good predictive ability and facilitate the interpretation of mechanism meanwhile.will become the main trend for predicting acute toxicity to aquatic organisms.