Abstract: Disclosure: M. Robinson: None. L. Meller: None. M.E. Patterson: None. Objective: To highlight the occurrence of premature ovarian insufficiency in cancer patients treated at a children’s hospital and to determine which patient characteristics or treatment modalities are associated with ovarian failure and subsequent recovery of ovarian function. Study design: A retrospective chart review. Setting: Rady Children’s Hospital San Diego. Subjects and Methods: Between August 2011 and August 2021, the cases of 36 patients with cancer and ovarian failure were reviewed. Data collected included type of cancer, age at diagnosis, types of chemotherapy used in treatment, whether a bone marrow transplant or radiation was part of the treatment plan, peak FSH value and age when this occurred, peak AMH value, whether GnRHa treatment was used, type of hormone replacement therapy used, and whether there was recovery of ovarian function. Results: The most common type of cancer identified in this group of patients was acute lymphoblastic leukemia (ALL) (13, 36.1%). The mean age of diagnosis was 8.5 ± 4.3 years and the mean age of peak FSH value was 12.6 ± 2.8 years. Nearly all patients (97.2%) were treated with alkylating agents as part of their chemotherapy regimen and 72.2% received some form of radiation. Most patients (26, 72.2%) also received some form of hormone therapy, most commonly transdermal hormone therapy (13, 36.1%) or oral contraceptive pill (10, 27.8%), and 15.8% of patients were treated with the GnRHa Lupron. Fertility planning was offered or discussed in 36.1% of patients. Ten patients (27.8%) were noted to have some degree of recovery in their ovarian function. Age at diagnosis and type of cancer treatment were significant predictors of recovery in multivariate regression modeling. Specifically, each year older in age was associated with a 30% decrease in odds of recovery (OR: 0.7, CI: 0.5-0.95, P = 0.035), and treatment with an alkylating agent without transplant was associated with a 3-fold increase in odds of recovery (OR: 3, CI:2.7-564, P = 0.007). Conclusion: This retrospective review demonstrates that, while uncommon, POI can occur in pediatric cancer survivors, emphasizing the importance of educating patients on the potential long-term effects of cancer treatment and routine surveillance for these complications. This study also confirmed that recovery of ovarian function is possible in these patients, especially when diagnosed at a younger age, so continued monitoring is essential. Presentation: 6/3/2024