Pollutants including insecticides have been recently reported to be a risk factor involved in various diseases. Permethrin, a member of the family of synthetic pyrethroids, is widely used as insecticide in agriculture and other domestic applications. To investigate possible cardiotoxicity, we had examined different concentrations of permethrin on the freshly isolated rat heart cells using the alkaline comet assay. A significant difference in % tail DNA between all concentrations of permethrin (5, 10, 20 microM) and vehicle (control) without enzymes and with Fpg-treated cells were measured. The results indicated that permethrin induced oxidative damage to purine bases in the heart cells. Pyrimidines oxidation was evaluated using Endonuclease III (Endo III), but the results did not reveal any significant changes. After permethrin exposure, cells were studied to evaluate their DNA repair capacity. A complete DNA repair at 10 and 20 microM was measured after 30 and 60 min of repair intervals. Significant change in plasma membrane fluidity at different depths of bilayer was measured following permethrin treatment. Membrane fluidity in the hydrophilic-hydrophobic region was reduced, while the hydrophobic inner resulted more fluid following permethrin treatment of heart cells. This work points to standardize conditions applicable to ex vivo cells following in vivo treatment in order to study the cardiotoxicity of insecticide.