Objective: The objective of this study was to evaluate gynecologists' knowledge of the WHI study, and its repercussions on their attitudes and practice 3 years after publication. Design: A self-administered, anonymous questionnaire containing 19 questions was sent to 6000 gynecologists, members of the Sao Paulo Society of Obstetrics and Gynecology. Results: The response rate was 24.2% (1453 completed questionnaires) with a sample error of 2.23% and confidence level of 95%. Although 95.9% of the respondents were aware of the WHI study, only 24.4% knew of all the other studies mentioned (HERS 1, HERS 11 and Million Women Study). Although 84.6% stated that the results of the WHI study could not be extrapolated to other forms of HT, 23.1% and 25.2%, respectively, stopped prescribing CEE or MPA, 63.7% decreased the dose, 55.2% opted for drugs such as bisphosphonates, tibolone and SERMS, and 46.3% began to prescribe tranquilizers, isoflavone and other natural medications. Moreover, 59.2% agreed that HT should be used for only 4-5 years. Prescriptions decreased significantly for all indications (p < 0.0001). The principal reason for physicians to discontinue HT in a patient was increased risk of breast cancer (62.3%), whereas, according to the physicians, the most important factor for the patients was fear of HT (80.3%). Conclusion: A high percentage of gynecologists in this study knew of the WHI study and followed its recommendations concerning cardiovascular prevention; consequently they changed their management of the treatment of postmenopausal women by restricting indications for HT and decreasing its duration of use and dose. (c) 2006 Elsevier Ireland Ltd. All rights reserved.