Background: While physician sex has been shown to impact salary even after adjusting for productivity, gender-based differences in clinical activity and reimbursement for oncologists and hematologists are not completely understood. We evaluated the differences in Medicare reimbursement for male and female physicians in medical oncology and hematology. Methods: A retrospective analysis using Centers for Medicare & Medicaid Services Physician and Other Supplier Public Use File (POSPUF) for the year 2017 was performed to identify charges and total payment information for individual oncologists and hematologists. Mean values were compared using two-sample t-test, and the medians were compared by Wilcoxon rank-sum test. Results: A total of 8553 oncologists and hematologists (2710 women and 5843 men) were included in the POSPUF in 2017. Female physicians submitted a mean of 16,754 fewer charges (95% CI, −19,696 to −13,812; P< .0001), collected a mean of $173,632 less in revenue (95% CI, −201,184 to −146,080; P< .0001), and submitted a mean of 5.65 fewer unique billing codes (95% CI, - 6.69 to - 4.61; P<.0001) compared to their male counterparts. Women represented 219 of the 1069 most highly productive oncologists and hematologists (20.4%) and collected a mean of $281,263 (95% CI, −417,517 to −145,008; P< .0001) less than similarly productive men. Conclusions: This study suggests that female oncologists and hematologists submit fewer Medicare charges and receive lower Medicare payments compared to male providers. Even among similarly productive hematologists and oncologists, women collected less revenue than men. Further research is required to explore causes for this difference.