Abstract Purpose Treatment of hematological malignancies carries the risk of lasting sterility. We aimed to identify fertility-related unmet needs. Methods The ‘Aftercare in Blood Cancer Survivors’ study is a cohort study of hematological patients who were in treatment-free remission for ≥ 3 years or stable under continuous oral medication. Female patients age 18–45 years and male patients age 18–65 years without a history of pre-treatment infertility were asked to answer a structured questionnaire including questions addressing fertility issues. Multivariable analyses were performed to detect risk factors. Results Of 1562 study participants, 1031 met the inclusion criteria for the fertility sub-study. A high proportion of patients (72.4%) received information about the risk of losing fertility, but only a minority (15%) took steps to preserve it. Female and older patients were less likely to be informed. A post-treatment wish for parenthood was expressed by 19.3% of patients. It was strongly associated with childlessness at time of diagnosis and could be fulfilled by 29.4%. Fulfillment of desired parenthood increased with increasing time from diagnosis and was low after allogeneic transplantation. Conclusions Female and older hematological patients are less likely to be informed about fertility-related issues than other patients. With societal changes towards first parenthood at higher age, the proportion of patients desiring a child after treatment is likely to increase. Fulfillment of desired parenthood remains challenging, especially after allogeneic transplantation. Implications for cancer survivors In patients likely to express a wish for post-treatment parenthood, fertility-related issues should routinely be addressed before gonadotoxic treatment is started.