OBJECTIVES: To evaluate the understanding of health professionals involved in first-trimester ultrasound screening of the ethical stakes involved by addressing three questions regarding: how much these professionals know about Down syndrome screening by nuchal translucency thickness measurement; their personal opinion with respect to this screening test; and their attitude with respect to their patients, in order to answer the question: 'Are ethical principles respected when women are proposed ultrasound screening during the first trimester of pregnancy?' METHODS: We studied the medical population in the east part of France by sending a questionnaire to each of 460 medical correspondents. This questionnaire attempted to evaluate the respondent's level of medical knowledge, their personal opinion with respect to first-trimester screening and their attitude towards their patients. We adapted the three-dimensional diagram designed by Marteau et al. to develop a measure of informed choice regarding screening. Only health professionals who were relatively well informed and adopted an autonomy-oriented approach were considered to be in a position to obtain true consent from their patients, respecting ethical principles in terms of competence and the autonomy of patients. RESULTS: We received 276 (60%) responses to the questionnaire. Only 31.9% of health professionals had an approach that facilitated obtaining true consent from their patients and respected the ethical principles of competence and patient autonomy; 46% were in favor of the screening test and adopted an autonomy-oriented approach but were poorly informed; and 15.4% had a directive-authoritarian approach combined with poor knowledge. Regression analysis showed that two independent factors (speciality (P = 0.031) and location of practice (P = 0.034)) affected the level of medical knowledge, and two independent factors (location of practice (P = 0.034) and the type of medical practice i.e. public or private (P < 0.05)) affected the opinion of health professionals about the screening test. Two independent factors (speciality (P < 0.001) and the age of the health professional (P = 0.02)) affected the attitudes of health professionals towards their patients. CONCLUSION: The answer to the question 'Are ethical principles respected when women are proposed ultrasound screening during the first trimester of pregnancy?' is clearly 'No'. Major effort is required to ensure that the decisions made by patients are based on a possibility of true choice.