At the University Hospital of Groningen maternal serum screening for fetal neural tube defects and Down's syndrome is available to pregnant women on their request. We have inquired into the reasons why women apply for serum screening and how this affects them. We did so by means of questionnaires sent to 200 women and by interviewing 20 women whose screening result indicated an increased chance of giving birth to a Down's syndrome child. The response percentage was 52.5. It appeared that opting for serum screening is seen as a self evident choice rather than a conscious one. In general, at the time of the decision, the women only saw the advantages of the test while possible consequences were often not taken into account. More than 70% of the women said they would apply for amniocentesis if they were told that they had an increased risk of having a baby with Down's syndrome. The confrontation with an increased risk of Down's syndrome then came unexpectedly and caused much distress. How to deal with the risk assessment results proved to be very difficult for these women. The difference in scale of the risk factor as established by the screening test compared with the original risk factor based on maternal age was interpreted by them as being of more significance than the statistical implication of the factor itself.