Abstract: The polymer-bound phosphonium salts are known as disinfectants, being important for drugs with prolonged activity and less toxicity, antifouling coatings and fiber finishing, water and air disinfection. The toxicity (expressed as the logarithm of oral lethal dose for mouse) was related to the structural features of a series of organic phosphonium salts by MLR. The structure of these compounds was modeled by molecular mechanics calculations and descriptors were then derived from the minimized structures. The structural features thus derived important for compound toxicity were derived by MLR combined with genetic algorithm for variable selection. Phosphonium salts toxicity was influenced by their electron distribution and steric factors.