To assess the information given to women during a maternal serum screening (MSS) programme, we prospectively applied a questionnaire to 504 pregnant women attending for amniocentesis after a screen-positive result. The survey based on 200 usable questionnaires (39.7 per cent of our study population) showed that MSS was imposed as mandatory by 41.5 per cent of providers and done without their patients' agreement by 16 per cent. After release of the test results, 6.5 per cent of women believed that they were carrying a Down syndrome-affected fetus and 21.5 per cent thought the risk was about 50-50. A total of 38.5 per cent of the pregnant women were not informed of the risk of miscarriage after amniocentesis and 67.5 per cent believed that there was no possibility of a false-negative result with MSS. Information given over the telephone was particularly poorly understood compared with information provided during an outcome visit, since women who learned of their test result during such a visit scored significantly higher (69 per cent) when questioned about the risk of carrying a Down syndrome-affected fetus, compared with women informed of their test results by telephone (38.7 per cent) or by letter (47 per cent). We therefore suggest routine consultation with an antenatal care professional before testing to enable pregnant women to give their informed consent to MSS.