AbstractDichlorvos (DDVP) is an organophosphorous pesticide with a high degree of dangerous effect towards the environment. We have investigated the growth and susceptibility to DDVP of halophilic bacteria isolated from Romanian salt lakes. The growth of four strains was affected by DDVP, which may be correlated with the rate constant values of DDVP disappearance from the saline solutions. This is due not to a chemical degradation in solution but to the diffusion process and namely DDVP penetration into the cell cytoplasm by an “organic-osmolyte” mechanism. The permeability coefficient P was calculated.