This investigation is based upon information from 820 pregnant women who replied to a questionnaire about AIDS during the period 17.4.1989-14.7.1989. The questions included sources of information, knowledge about routes of infection and risk groups and the extent of spread of infection and disease in the population. 95% agreed to participate. Knowledge had been obtained primarily via the electronic media, while the health services had limited significance. The employment of sources of information depended on age and occupation. Apart from knowledge about the risk involved in breast feeding, the women were, in general, well informed about routes of infection. Knowledge about risk groups and the current extent of spread of infection was, on the the other hand, deficient. Defective knowledge was concentrated in groups which may be characterized by age (less than 24 years) and occupation (trained and untrained workers and the group of "other occupations"). Information obtained from health staff was connected with better knowledge about the extent of spread of infection. The majority of women desired routine information about AIDS in connection with antenatal control. Prophylactic measures should be based, among other things, on knowledge about development in the knowledge in the population and its employment of sources of information, so that specific information may be directed to certain groups of the population by using the most frequently employed and most effective routes of information. The knowledge of population groups, the attitudes and behaviour should be followed continuously.