A questionnaire investigation was undertaken among young Greenlanders in vocational training about their knowledge of AIDS and their sexual habits as a link in monitoring of the course of AIDS prophylaxis in Greenland. The investigation was anonymous and was carried out in the vocational colleges with assistance of a contact person in the college. All of the students who were present on the day of investigation (264 out of 326 students) participated. The investigation revealed that 3/4 had basic knowledge about AIDS but their knowledge about the routes of infection was less certain. The average age for commencement of sexual activity was 18.9 years for men and 17.3 years for women. Although the investigation revealed that a number of the participants had sexual habits which scarcely differed from those in other countries, the average number of partners within the past year was stated to be 7.5 for men and 4.4 for women. Information which can provide young people with better knowledge about AIDS should be given via colleges and health service institutions to a greater extent. It is also recommended that materials should be developed which are directed particularly to high-risk groups.