BACKGROUND: We examined the impact of race, education, and household income on changes in rates of discontinuation and initiation of hormone therapy before and after release of the Women's Health Initiative estrogen plus progestin trial results. METHODS: We conducted an observational cohort study of 221 378 women aged 40-80 years enrolled in five health maintenance organizations to estimate the prevalence and rates of discontinuation and initiation of estrogen plus progestin and estrogen only between September 1, 1999, to June 31, 2002 (baseline), and December 31, 2002 (follow-up). We identified the census block group for each participant by geocoding her 2003 residential address. We categorized women into racial, education, and income groups based on the distribution of these characteristics in her community from year 2000 census data and the distributions of these characteristics within her HMO. RESULTS: There were significant differences in estrogen plus progestin and estrogen only prevalence by race, education level, and household income, and in estrogen plus progestin initiation by race and education level, but not by household income at follow-up. However, there were no differences by community race, education, or household income in change in the prevalence of either hormone therapy use at follow-up or in the rates of hormone therapy discontinuation or initiation from baseline to follow-up. CONCLUSIONS: Given the wide spread media attention to the Women's Health Initiative estrogen plus progestin trial results, our findings suggest comparable dissemination of this information across diverse socioeconomic groups.