Although rheumatoid arthritis (RA) is more predominant in women, the reasons for this are unclear. Many studies have examined the effects of estrogen on the risk and severity of RA, but the results are conflicting and controversial. A new study using data from the Women’s Health Initiative (WHI) clinical trials on hormone replacement therapy found that there were no significant differences in the risk of developing RA or the severity of RA between postmenopausal women who were on hormone replacement therapy and those who took placebos. The study was published in the March issue of Arthritis Care & Research (http://www.interscience.wiley.com/journal/arthritiscare).