The hypothesis that the parents and siblings of children with nephrotic syndrome are more likely to develop psychosocial problems than those of healthy children was tested. Seventy-nine siblings from 36 such families were compared with 79 healthy children from closely matched families using interviews, parent rating scales, teachers' reports, and psychological tests. Although few striking differences were found between the two groups, the findings suggest several areas of increased vulnerability among the parents and siblings of children with nephrosis. Parents often denied the existence of apparently stressful events, but the personality profiles of the siblings suggested decreased social confidence and a lesser degree of self-acceptance. Evidence of inhibition, such as less aggression and poorer academic performance, were also described in response to questions in the interview. These results should prove useful to clinicians in the management of families of children with this or other chronic illnesses.