to　Rat　and　Mouse　using　simple　2D　descriptors.　The　Read-Across　similarity　descriptors　and　2D　descriptors　were　also　combined　to　develop　the　quantitative　read-across　structure-activity　relationship　(q-RASAR)　models.　Interspecies　toxicity　(iST)　correlation　was　also　explored　between　the　two　rodent　species.　All　developed　QSAR,　qRASAR　and　iST　models　met　the　state-of-the-art　validation　criteria　and　were　applied　for　toxicity　predictions　of　hundreds　of　untested　PFASs　in　true　external　sets.　Subsequently,　we　performed　the　priority　ranking　of　the　untested　PFASs　based　on　the　model　predictions,　with　the　mechanistic　interpretation　of　the　top　20　most　toxic　PFASs　predicted　by　both　QSAR　and　q-RASAR　models.　The　two　univariate　iST　models　were　also　used　for　filling　the　interspecies　toxicity　data　gap.　Overall,　the　developed　QSAR,　q-RASAR　and　iST　models　can　be　used　as　effective　tools　for　predicting　the　oral　acute　toxicity　of　untested　PFASs　to　Rat　and　Mouse,　thus　being　important　for　risk　assessment　of　PFASs　in　ecological　environment.