BACKGROUND: Approximately half of all pregnancies in the United States are unintended. However, women who are diagnosed with cancer in their reproductive years may be a unique population. This study examines the prevalence of and identifies factors associated with unplanned pregnancy among cancer survivors. MATERIALS AND METHODS: Female cancer survivors aged 22–45 years, diagnosed between ages 20–35 years and at least 2 years postdiagnosis, and women with no history of cancer were interviewed about their reproductive histories, including pregnancy intention. Using a random matching process, comparison women were assigned an artificial age at cancer diagnosis equal to that of her cancer survivor match. An adjusted Cox model was fit examining time to unintended pregnancy after cancer for each of 1,000 matches. Cox proportional hazards models were also fit to assess associations between participant characteristics and unplanned pregnancy after cancer among survivors. RESULTS: Cancer survivors (n = 1,282) and comparison women (n = 1,073) reported a similar likelihood of having an unplanned pregnancy in models adjusted for race, income, history of sexually-transmitted infection, and history of unplanned pregnancy before diagnosis (adjusted hazard ratio [aHR] 1.06, 95% simulation interval 0.85–1.36). After adjusting for confounders, unplanned pregnancy among survivors was associated with age