OBJECTIVE - To describe the psychological impact of positive islet cell antibody (ICA) screening results in children and adults, as well as their parents and spouses. RESEARCH DESIGN AND METHODS - The psychological impact of ICA screening results was assessed subsequent to subjects' being informed of ICA-positive (ICA(+)) status and was re-evaluated 4 months later. Impact was measured using the state subscale of the State-Trait Anxiety Inventory (STAI) for adults or the State-Trait Anxiety Inventory for Children (STAIC), as well as structured interviews. A total of 34 ICA(+) children, 34 ICA(+) adults, 33 parents, and 25 spouses were evaluated. RESULTS - Al initial notification of ICA(+) status, clinically and statistically significant anxiety was observed in ICA(+) children and adults and their family members (P < 0.001). Parents of ICA(+) children were more anxious than spouses of ICA(+) adults (P < 0.05). Child and parent anxiety were significantly correlated (P < 0.05); more-anxious children lived with more-anxious parents. No significant association was found between ICA(+) adults' initial anxiety and their spouses' anxiety. For ICA(+) participants and their family members, anxiety dissipated to normal levels in 4 months (P < 0.02). ICA(+) children were less likely than parents to believe they would ever develop insulin-dependent diabetes mellitus (IDDM). Nevertheless, 52% of ICA(+) children and 24% of ICA(+) adults endorsed lifestyle or behavior changes as a result of their ICA(+) status. Behavior change was associated with greater initial anxiety in both children and adults (P < 0.05 for both). CONCLUSIONS - These data suggest that notification of ICA(+) status has both emotional and behavioral impact. Initial notification of ICA(+) status is associated with considerable anxiety in both ICA(+) individuals and their family members. In most cases, this initial anxiety appears to dissipate to normal levels over time. However, many ICA(+) individuals report initiating lifestyle or health behavior changes in an effort to delay or prevent IDDM onset.