Since pyrethroids are involved in reactive oxygen species production and no investigations have yet been performed on smooth muscle cell integrity, we studied the influence of permethrin- and cypermethrin-treatment on rabbit aorta using confocal laser scanning fluorescence microscopy, which allows cell viability to be assessed within the wall of living rabbit aorta. The data obtained show that the pyrethroid-treatment (10-100μM) impairs the smooth muscle cell viability. A double-labeling protocol allowed us to distinguish cytotoxic effects of permethrin- and cypermethrin-treatment in aortic rings. In conclusion, permethrin seems to induce more oxidative stress on the aorta wall than that cypermethrin does.