Neurological, cognitive and behavioural development were assessed in a group of 21, 8- to 10-year old children whose mothers took coumarins during pregnancy. Findings were compared with those in a group of 17 control children. The study was performed to test whether it is feasible to carry out a reliable retrospective study of late effects of prenatal exposure to coumarins. This turned out to be the case. In this small pilot study, no statistical significant differences were found between the study and control group, nevertheless a few findings were remarkable. One child showed severe neurological abnormalities, which may be due to prenatal exposure to oral anticoagulants. The children with the lowest scores on the neurological assessment and the lowest IQ-scores, were found in the exposed group. Obviously, the number of children in this study is too small to conclude if there has been definite effects from coumarin, but these results indicate that a large follow-up study is required. In the present paper, we have shown that such a study is feasible.