The effects of 8-days treatment with 17alpha-estradiol (33.3 microg/kg) and progesterone (1.7 mg/kg) on plasma lipids and fatty acid composition of plasma phospholipids were examined in intact (INT) and bilaterally common carotid arteries occluded (BCO) male Wistar rats. Significant decrease of triglyceride level was found in BCO rats after the estradiol treatment. Both hormones elevated proportion of 18:1n-7 fatty acid in INT, but they failed to have such an effect in BCO. Estradiol increased 22:5n-3 and total n-3 polyunsaturated fatty acids (PUFA) in intact, and decreased 18:2n-6 in BCO rats. Significantly lower level of total n-3 was found in progesterone-treated than in estradiol-treated BCO rats. Given that n-3 PUFA have many beneficial effects on cell and tissue function, while n-6 PUFA have mostly the opposite effects, estradiol, rather than progesterone, was seen to improve plasma lipids and phospholipids FA profiles in INT and BCO animals. Estradiol significantly elevated the estimated activity of delta9-desaturases and progesterone of delta5-desaturase in BCO group, with no effects in INT rats.