ABSTRACT: Cyproterone acetate 2 mg/ethinylestradiol 35 µg, an estrogen/progestogen treatment with anti-androgenic properties, shares a thromboembolism risk with combined hormonal contraceptives. Educational materials (i.e., direct healthcare professional communication, patient information card, prescriber checklist) were distributed to physicians to increase risk awareness.The objective of this study was to measure physician knowledge of thromboembolism risk of cyproterone acetate 2 mg/ethinylestradiol 35 µg and ascertain whether physicians received the educational materials.A cross-sectional web-based physician survey of recent prescribers of cyproterone acetate 2 mg/ethinylestradiol 35 µg in Austria, the Czech Republic, France, the Netherlands, and Spain was conducted. Sampling targets for physician specialty were based on country-specific prescribing patterns. Frequency of correct responses was calculated for 14 knowledge questions.Among 759 physician respondents (37% of obstetricians/gynecologists, 42% of general practitioners, 20% of dermatologists), 51% received one or more of three educational materials. Knowledge was highest (?80%) for symptoms of possible deep vein thrombosis, pulmonary embolism, and cerebrovascular accident; most important risk factors for thrombosis; use in smokers; indication for moderate-to-severe acne; and understanding that cyproterone acetate 2 mg/ethinylestradiol 35 µg should not be used for contraception alone. Knowledge varied for contraindications, myocardial infarction symptoms, other risk factors for thrombosis, instructions regarding anticipated prolonged immobilization, and selected concomitant medical conditions. Knowledge was lower regarding prescribing cyproterone acetate 2 mg/ethinylestradiol 35 µg for acne only after failure of topical therapy or systemic antibiotics. Generally, knowledge did not vary by physician specialty, receipt of educational materials, number of patients prescribed cyproterone acetate 2 mg/ethinylestradiol 35 µg in the previous 3 months, and years in practice.Knowledge was generally high for thromboembolism risk and varied for more complex or infrequent topics.