Objective: The aim of the study was to examine whether physicians who are better informed about large, published hormone therapy (HT) trials (eg, the Women's Health Initiative) are more likely to prescribe HT for menopausal symptoms. Methods: US obstetricians/gynecologists and primary care physicians completed a 15- to 20-minute Internet-based survey. Knowledge was assessed via nine true-false statements about HT trials (range: 0-9). Prescribing practices were assessed via six case studies with a seven-point response scale of "extremely unlikely" to "extremely likely" in relation to treatment options (range: 6-42). The primary analysis examined the correlation between HT trial knowledge and likelihood of prescribing HT. Secondary analyses gauged knowledge and prescribing practices based on practice type, sex, and years in practice. Results: Among 501 physicians who completed the survey (representing 10.7% of those invited; median age: 51.0 y; female: 26.9%; obstetricians/gynecologists: 49.9%; median 19.0 y in practice), HT knowledge (mean [SD] 3.8 [2.3]), and prescribing (mean [SD] 24.5 [5.6]) exhibited a statistically significant, moderate positive correlation (0.30; 95% CI, 0.21-0.37; P < 0.0001). Obstetricians/gynecologists were significantly (P < 0.0001) more knowledgeable and more likely to prescribe HT than primary care physicians. Male physicians were more likely (P < 0.05) to prescribe HT but not more knowledgeable about it than female physicians. Knowledge (but not likelihood of prescribing) significantly increased as a function of years in practice. Conclusions: Physicians who are more knowledgeable about large, published HT trials are more likely to prescribe HT for menopausal symptoms.