Cloning of the COL4A5 gene has now made possible prenatal testing for Alport syndrome with X-linked dominant inheritance. We interviewed 27 females and 24 males with Alport syndrome to evaluate their knowledge of the disease and its transmission, and their attitudes to prenatal testing. Twenty-two males and 8 females were on renal replacement therapy. In all cases transmission was compatible with X-linked disease. Only 59% of the interviewees (74% of women, 42% of men) knew that gender was the major determinant in progression of the disease. Knowledge of the mode of inheritance was adequate in only 25%, in both sexes. Seventy percent of the participants (78% of women, 63% of men) would use prenatal testing. Of the women in favor of prenatal diagnosis, 67% and 39% would terminate pregnancy in the case of an affected male or female fetus, respectively. Of the men in favor of prenatal diagnosis, 53% would consider termination of an affected fetus. In summary, a majority would use prenatal testing, but only one or two thirds of them wished to use selective abortion. As in other inherited disorders, there is a discrepancy between the demand for prenatal diagnosis and the decision to terminate pregnancy. Most of the participants who would terminate a pregnancy had, however, little knowledge of the clinical and genetic aspects of Alport syndrome on which to base such a decision. An important aspect of genetic counselling is to assist consultants in reaching a decision regarding future reproductive behaviour which is appropriate to their situation. This study underlines the need to improve education and counselling to assure appropriate use of prenatal testing.