In this study the relationship between the South African Grade 11 Life Sciences curriculum documents, HIV and AIDS knowledge and behavioural preferences of students was investigated. The Life Sciences curriculum and textbooks used in Grade 11 Life Sciences were analysed to determine the curriculum ideology of the subject and concepts related to HIV and AIDS that are prescribed for teaching with the aim of educating students about HIV and AIDS and promoting safe behaviour. Life Sciences and non-Life Sciences students were compared to determine whether academic HIV and AIDS knowledge taught in Life Sciences was related to functional HIV and AIDS knowledge and behavioural preferences. Findings indicate that Life Sciences does not promote safe behaviour related to HIV and AIDS. Furthermore Life Sciences is knowledge-oriented and integrates HIV and AIDS knowledge as extra content. In addition Life Sciences does not have a clear curriculum ideology for HIV and AIDS education even though it has characteristics of various curriculum ideologies with greater emphasis on the scholar academic ideology. The Life Sciences curriculum makes provisions for the construction and application of HIV and AIDS knowledge, but it does not provide guidance with regards to application of knowledge. Moreover textbooks are not consistent with regard to presentation of content and do not present sufficient content for meaningful application in everyday life. Results also showed that academic HIV and AIDS knowledge improves some students’ knowledge of functional HIV and AIDS knowledge. It was also found that HIV and AIDS knowledge does not significantly correlate with some students’ behaviour presumably because students have difficulty in relating Life Sciences knowledge to real life. Consequently some students do not fully know some HIV and AIDS concepts, and they rely on alternative means to respond to questions for which they do not have the necessary content knowledge. It was also found that some students do not take ownership of social problems related to HIV and AIDS. The researcher believes that there is a need to review HIV and AIDS education in Life Sciences by basing it on a precise curriculum ideology that will ensure that suitable scientific content, which may lead to behaviour transformation, is integrated.