Knowledge of a genetic disease in an individual raises the questions of whether and how this information should be communicated to his or her family. The aim of the present study was to provide factual information about attitudes towards an unsolicited approach from a physician regarding genetic counseling within affected families. We performed a questionnaire study among patients with alpha(1)-antitrypsin deficiency, their examined and unexamined relatives, and a control group of Danish citizens. Of 2,146 subjects, the questionnaires were returned by 1,761 (82%), and 1,609 (75%) wanted to participate. Stepwise logistic regression showed that phenotype/subgroup, having descendants, and being female were significantly related to the approval of an unsolicited approach and the informing of relatives. Provided it was difficult for the index case to inform relatives about their risk and about his/her disease, then a total of 75.8% would not proscribe an unsolicited approach by the physician. Most of those for proscribing an unsolicited approach found that relatives should be informed in advance by the index case. The control group of randomly chosen Danes was the most skeptical towards an unsolicited approach. Most individuals found that genetic risk information should be shared with relatives at-risk. A flexible information policy by the health care system based on active approach towards relatives is acceptable to 75 to 95% of individuals in order to ensure diffusion of genetic risk information within families segregating for a genetic disease with a modifiable outcome.