Background: Adolescent and young adult (AYA) cancer patients (15-39 years of age) often report health insurance concerns and financial toxicity due to their life-saving treatment. AYAs often have limited experience with healthcare prior to their diagnosis, which may limit their understanding of health insurance concepts, coverage, and costs. To describe AYA health insurance experiences, expectations, and literacy, we conducted semi-structured interviews with AYA cancer patients and survivors. Methods: Eligible participants were 18-39 years, diagnosed with cancer, and insured. Participants were recruited through an AYA cancer navigation program in Utah from 10/2019-03/2020. Participants were purposively sampled to achieve equal age strata (18-25 vs. 26-39), as patients under 26 often remain on their parents policy. Individual interviews were recorded, transcribed, and analyzed. Inductive qualitative analysis was conducted to describe their experiences with and understanding of their insurance. We calculated descriptive statistics of demographics and the Health Insurance Literacy Measure (HILM), a continuous measure ranging from 0-84 (higher scores indicate higher comfortability and literacy). Associations of age (18-25 vs. 26-39) and policy holder (yes vs. no) with HILM score were evaluated with t-tests. Results: AYAs (N = 24) were nearly even by gender, female (58%), primarily heterosexual (92%), Non-Hispanic White (79%), and had at least some college (92%). Less than half of participants were policy holders (41.7%). Three themes emerged from analysis: 1) Lack of knowledge and experiential learning throughout treatment, 2) Unclear expectations of health insurance, and 3) Difficulties navigating coverage and the complex systems. Most AYAs were unaware of the specifics of their coverage and how their insurance plan impacted their costs. Most AYAs were surprised at the lack of coverage and high costs they encountered during treatment. Most AYAs experienced substantial difficulty navigating coverage issues, particularly the appeals process. The mean HILM score was 55.63 (SD = 10.06), no differences by age group or policy holder status. Conclusions: AYAs with cancer report substantial difficulty navigating the complex health insurance system and demonstrate low levels of health insurance literacy. Health insurance education focusing on insurance concepts (e.g., cost-sharing mechanisms) may help AYAs better manage costs and enable them to make informed health insurance decisions despite being at higher risk for financial toxicity.