Objective: To compare markers of fertility and ovarian reserve between cancer survivors and cancer-free women with and without polycystic ovary syndrome (PCOS). Design: Furthering Understanding of Cancer, Health, and Survivorship in Adult (FUCHSIA) Women's Study—a population-based cohort study. Setting: Not applicable. Patient(s): Female cancer survivors (n = 1,090) aged 22–45 years, diagnosed between ages 20 and 35 years, and at least 2 years after diagnosis; 369 participated in a clinic visit. Three hundred seventy-four reproductive-aged women without cancer also completed a clinic visit. Intervention(s): None. Main Outcome Measure(s): Infertility, time to first pregnancy after cancer diagnosis, and measures of ovarian reserve (antimüllerian hormone [AMH] and antral follicle count [AFC]). Results: Seventy-eight cancer survivors (7.2%) reported a PCOS diagnosis, with 41 receiving gonadotoxic treatment. Survivors with PCOS exposed to gonadotoxic treatment (odds ratio [OR] 2.3, 95% confidence interval [CI] 1.2–4.5) and unexposed (OR 3.4, 95% CI 1.7–6.9) were more likely to report infertility than unexposed survivors without PCOS and were more likely to have fewer children than desired (exposed: OR 2.1, 95% CI 1.0–4.2; unexposed: OR 3.0, 95% CI 1.4–6.8). After adjusting for age, comparison women with PCOS had the highest markers of ovarian reserve (AMH: 2.43 ng/mL, 95% CI 1.22–4.82 ng/mL; AFC: 20.7, 95% CI 15.3–27.8), and cancer survivors without PCOS treated with gonadotoxic agents had the lowest levels (AMH: 0.19 ng/mL, 95% CI 0.14–0.26 ng/mL; AFC: 7.4, 95% CI 6.4–8.5). Conclusion(s): Despite having higher AMH and AFC on average after cancer treatment, cancer survivors with PCOS were less likely to meet their reproductive goals compared with survivors without PCOS.