To ensure successful implementation of genetic screening and counselling according to patients best interests, the attitudes and motives of the public are important to consider. The aim of this study was to apply a theoretical framework in order to investigate which individual and disease characteristics might facilitate the uptake of genetic testing. A questionnaire using an extended version of the Theory of Planned Behaviour was developed to assess the predictive value of affective and cognitive expected outcomes, subjective norms, perceived control and uncertainty avoidance on the intention to undergo genetic testing. In addition to these individual characteristics, the predictive power of two disease characteristics was investigated by systematically varying the diseases fatality and penetrance (i.e. the probability of getting ill in case one is a mutation carrier). This resulted in four versions of the questionnaire which was mailed to a random sample of 2400 Norwegians. Results showed genetic test interest to be quite high, and to vary depending on the characteristics of the disease, with participants preferring tests for highly penetrant diseases. The most important individual predictor was uncertainty avoidance.