To compare the effect of oral and transdermal estrogen replacement therapy (ET) on circulating interleukin-6 (IL-6) in post-menopausal women. Prospective open trial study in 55 healthy hysterectomized postmenopausal women with a mean age of 52 years. Twenty-seven women received oral conjugated equine estrogens (0.625 mg daily) and the remaining 28 received transdermal estrogen replacement therapy (50 microg/day) during 6 months. At baseline both groups were similar as to age, body weight, and body mass index as well as serum levels of LH, FSH, 17-beta estradiol (E2) and IL-6. Baseline elevated IL-6 levels decreased significantly (p