Importance Cancer is the leading disease-related cause of death among adolescents and young adults (AYAs), but little is known about the care that AYA patients with cancer receive at the end of life (EOL). Objective To evaluate the intensity of EOL care among AYA cancer patients. Design Cross-sectional study using cancer registry and electronic health record data. Setting Kaiser Permanente Southern California (KSPC), an integrated health care delivery system. Participants 663 AYA patients with either (1) stage I-III cancer and evidence of cancer recurrence or (2) stage IV cancer at diagnosis who received care in KPSC and died in the years 2001–2010. Patients were eligible if they were aged 15–39 at death. Main Outcome Measures Chemotherapy use in the last 14 days of life, intensive care unit (ICU) care in the last 30 days of life, more than one emergency room (ER) visit in the last 30 days of life, hospitalization in the last 30 days of life, and a composite measure of medically intensive EOL care comprising any of the aforementioned measures. Results 11% of patients (72/663) received chemotherapy within 14 days of death. In the last 30 days of life, 22% of patients (144/663) were admitted to the ICU; 22% (147/663) had >1 ER visit; and 62% (413/663) were hospitalized. Overall, 68% (449/663) of subjects received at least one medically intensive EOL care measure. Conclusions and Relevance Most AYA patients receive at least one form of medically intensive EOL care. These findings suggest the need to better understand EOL care preferences and decision-making in this young population.