The emotional impact of carrier detection for CF was assessed in a group of adults tested before 1992. Of the 200 adults who received a mailed questionnaire, 70% participated. One third were CF gene carriers. The Health Orientation Scale (HOS) was used to evaluate perceived feelings about three situations: (a) How would you describe your feelings about yourself when you consider your test result? (b) How do you think most people feel when they are told that they carry the CF gene? (c) How do you think most people feel when they are told that they do not carry the CF gene? Comparing the profiles of CF carriers and non-carriers, we found that carriers had significantly less positive feelings about themselves than non-carriers. Carriers as well as non-carriers attribute significantly more negative feelings to most carriers of the CF gene than to most non-carriers. Moreover, carriers of the Cf gene attribute more negative feelings to other CF carriers than to themselves. Analysis of variance revealed a significant effect of carrier status on self-description, as well as a significant effect of carrier status and degree of kinship with a CF patient on feelings attributed to most carriers. Although these results suggest some danger of stigmatization of CF carriers, the cognitive bias of 'illusory superiority' seems to counterbalance some of its effects.