Background: The COVID-19 pandemic has affected oncology practice in a variety of ways. We sought to evaluate the impact on pediatric oncology parent and young adult (YA) patient experiences, concerns, and perceived stress. Methods: We conducted a cross-sectional Internet-based survey of parents and YA patients in the pediatric oncology and survivorship clinics at Stanford between June-December 2020. Patients were recruited in person by clinic staff or through the electronic patient health portal. Surveys (available in English and Spanish) included the NIH Perceived Stress Scale (PSS-10) and investigator-developed questions evaluating clinical practice changes, concerns about health and cancer care, and pandemic-related challenges. Bivariate analyses evaluated associations between demographic, clinical, and pandemic-related factors and (a) concern about the pandemic affecting health and cancer care, and (b) perceived stress. Results: Among 81 participants (66 parents, mean age 41.6 ± SD 9.6; 15 YAs, mean age 21.9 ± 8.4 years), 37% self-identified as Hispanic/Latino, 36% non-Hispanic white, and 21% Asian. Twenty-eight percent were on treatment and 47% had completed treatment (79% < 5 years prior). Thirty percent reported cancer-related appointment changes, largely rescheduling (75%) and/or switching to telehealth (42%). Nearly half (45%) of parents and 27% of YAs reported feeling ‘very’ or ‘extremely’ concerned about the pandemic affecting their child’s/their health or cancer care. Race/ethnicity emerged as the only demographic feature that was significantly associated with high concern (p = 0.018), with 57% of Hispanic/Latino and only 21% of non-Hispanic white respondents reporting high levels of concern. Specific concerns included fear of severe infection, immunosuppression, and whether infection would change treatment and compromise effectiveness. Parents and YAs reported ‘a lot’ or ‘a great deal’ of challenges in their personal/family life (61%) and work/professional life (48%). Among these were having less support from friends/family (35%), reduced wages/work hours (31%), and job loss (20%) with 20% reporting ≥ 3 challenges. On the PSS-10, stress in the past month was high for parents (mean 30 ± 4) and YAs (mean 31 ± 5.1) on a scale of 0-40. Risk factors for higher stress included: male gender (p = 0.028), less support from family/friends (p = 0.002), and experiencing ≥ 3 pandemic-related challenges (p = 0.013). Conclusions: Our findings confirm the prevalent worry and stress that pediatric oncology patients and families are experiencing during the COVID-19 pandemic. Better communication about cancer care service changes may help to alleviate some concerns. Supportive care resources may also help patients and families cope with psychosocial stressors, particularly among at-risk groups.