Mice, fish, gastropods and polychaetes were injected with the venoms of 23 species of Conidae. The venoms of Conus magus, C. striatus and C. stercusmuscarium quickly immobilized fish and were lethal to mice. Lethal and near lethal doses of posterior duct venom from C. magus produced a spastic paralysis in mice whilst lethal and near lethal doses of anterior duct venom of C. magus, posterior duct venom of some specimens of C. striatus and the venom of C. stercusmuscarium caused flaccid paralysis of the skeletal musculature of mice. Venom from some specimens of C. striatus induced circling movements in mice. The venoms of C. omaria, C. aulicus, C. episcopis, C. ammiralis and C. tigrinus quickly paralysed the gastropod Melarapha scabra. The polychaete Phyllodoce malmgremi was paralysed or partially paralysed by the venoms of C. litteratus, C. millepunctata, C. pulicarius, C. figulinus, C. arenatus, C. imperialis, C. virgo, C. rattus, C. eburneus and C. planorbis. Analysis of well-authenticated records of human injury inflicted by Conidae supports the contention that only piscivorous Conidae pose a threat to man. The structure of the radular teeth of Conidae provides a means of distinguishing between piscivorous, vermivorous and molluscivorous species.