Editor—On the basis of family history, it is possible to identify subjects at significantly increased genetic risk of breast or colorectal cancer.1 2 Evaluation of the benefits of screening these patients to facilitate early diagnosis and treatment forms the subject of continuing studies. For colorectal cancer, the benefits of colonoscopic surveillance have been reported,3 but for breast cancer more data are needed to confirm the value of mammographic screening.4 At present, patients with a significant family history who seek advice from their general practitioner are likely to be referred to a cancer genetics clinic and offered screening. If further research confirms the benefits of screening for patients at increased genetic risk, effective strategies for their ascertainment in primary care will be needed. One possible method is a postal family history questionnaire sent to the patient by their general practitioner. We report elsewhere on the effectiveness of this approach.5 An important issue is whether this method of ascertainment raises anxieties, particularly among the majority of patients who do not have a significant family history. The collection of cancer family history information constitutes a form of screening. There is a large body of evidence that health related screening can have unintended adverse effects, the most studied of which is raised anxiety, particularly among those found to be at an increased risk.6 As knowledge of the genetic component of common diseases increases,7 more patients may be asked to provide information about their family history. It is therefore timely to consider whether such a task may inadvertently raise general levels of anxiety or worries about the disease in question. To our knowledge, there have been no previous studies of the psychological consequences of screening using a postal questionnaire to obtain information about relatives affected by cancer. …