Screening is supposed to create less anxiety among first-degree relatives of diabetic patients where the risk of developing diabetes already is well known. It has also been argued that screening of a general child population should never be performed unless identified high-risk individuals can be offered intervention to prevent diabetes. However, the empirical data are scarce, especially regarding what opinions patients or their parents have of these matters/issues themselves. We have therefore tried to evaluate mothers' attitudes to and ethical views on participation in a research screening for prediabetes in an unselected birth cohort. All 21,700 mothers of children in southeast Sweden born between 1 October 1997 and 1 October 1999 were asked to participate in ABIS (All Babies in Southeast Sweden). They were given information about the design of the study and that HLA types and autoantibodies will be determined in order to predict diabetes, but that no prevention of diabetes will be offered unless future studies show effective methods. After informed consent, 78.6% of mothers let their babies participate (17,055 children) despite a quite laborious study protocol. Explorative in-depth semistructured interviews were performed in 21 mothers, of whom 15 were strategically selected to get as many various attitudes as possible and of whom 6 chose not to participate in ABIS. All interviewed mothers were positive to the ABIS project. We conclude that a well-designed screening program to detect individuals in the general population with high risk of developing diabetes does not evoke anxiety nor severe ethical conflicts.