INTRODUCTION Australia has implemented a nation-wide program providing HPV vaccination to girls at school. To date, there are no published studies that explore knowledge about HPV and HPV vaccine post-implementation of the national school-based HPV vaccination program. METHODS A purposive sample of schools was selected to reflect a range of vaccination coverage (high versus lower uptake), and different school types (Catholic, Independent or Government). Semi-structured focus groups and interviews were conducted with girls and their parents respectively, until saturation was reached. Transcripts were analysed, letting themes emerge from the data. RESULTS A core theme from both girls and parents was lack of knowledge. Supporting themes were lack of knowledge of HPV, lack of knowledge of vaccine, and realisation of their lack of knowledge. Their lack of knowledge was common in three areas: what HPV is, how HPV is transmitted, and the HPV and cervical cancer connection. The lack of knowledge about HPV vaccination was reflected in what the vaccine protects against, how the vaccine works, HPV vaccination recommendations, the vaccine and Pap smear connection, and myths about HPV vaccination. Both girls and parents wanted more information, had a tendency to defer responsibility, and parents expressed judgment of themselves as parents. DISCUSSION Low levels of knowledge and understanding about HPV vaccination among adolescents and parents have implications for adolescents' future health practices, including sexual risk behaviour, condom usage, and cervical screening. Reasons for the low levels of knowledge are explored, as are implications for school-based educational interventions.