People's knowledge of screening tests for which they are eligible and which they may have undergone is frequently low. The aim of the current study is to determine the extent to which this is due to how a test is offered and explained. Routine consultations (n = 102) between midwives, obstetricians and pregnant women were tape-recorded to determine how a routine screening test for fetal abnormalities (maternal serum alpha-fetoprotein) is presented. The test was presented in the vast majority of consultations. Overall, little information was provided about the test, the conditions screened for, and the meaning of either a positive or a negative result. Screening was presented in such a way as to encourage women to undergo the test. The way in which routine prenatal screening is presented is unlikely to maximise informed decisions about whether to participate in this screening programme. Factors likely to be influencing test presentation include knowledge, attitudes and skills of staff, as well as the attitudes of pregnant women. The results of this study highlight a need to train the heath professionals implementing screening programmes in how to inform people fully about low probability but serious events without alarming them unduly, or reassuring them falsely.