The aim of this study was to study the effect of a teaching unit on upgrading university-nursing students' knowledge and attitudes about genetic counseling. The study used pre- test, posttest with no control group design. All nursing students (100) who accepted to participate in the study and enrolled in the Maternity and Gynecological-nursing course, during the second semester of the third academic year 1999-2000, at the Faculty of Nursing, Alexandria University, were involved in the study. A self-administered questionnaire sheet was used to assess nursing students' knowledge about genetic counseling, while a 3-point Likert-like scale was used to assess their attitudes towards it. The content of six-hours' teaching unit -about genetic counseling was taught to students by the researchers based on their needs. The study revealed a general lack of knowledge among nursing students regarding basic information about genetic counseling, where poor total score of knowledge was obtained by all of them in the pre-test. In addition, the pre-test revealed that negative attitude was found in about half of the nursing students. The teaching unit had an obvious effect on the nursing students' knowledge and attitudes regarding genetic counseling, as the total score of their knowledge and attitudes had improved after implementation of the teaching unit. Moreover, there was a significant relationship between nursing students' knowledge and attitudes towards genetic counseling before and after implementation of the teaching unit. Therefore, a negative attitude was found with poor total score of knowledge in the pre-test and positive attitude was found with good total score of knowledge in the post-test. So, there is a need to improve knowledge and change attitude of nursing students about genetic counseling. As well as genetic counseling should be included in the university-nursing curriculum and should be reviewed periodically to accommodate the relevant fast change in the science and technology of genetics. Moreover, nursing students must be informed about the different community resources, which offer the genetic counseling services.