e13513 Background: Having physicians who practice at multiple sites may increase patients’ access to care, but also burden physicians Gynecologic oncologists (GO) are increasingly practicing at more sites across a larger geographic area, but the degree to which medical oncologists (MO), surgical oncologists (SO) or radiation oncologists (RO) are also doing so is unknown. Methods: We conducted a retrospective, observational study using data from the 2020 Physician Compare National Dataset. We included GO, MO, SO, RO, as determined by self-reported specialty. Practice sites with incomplete street addresses were excluded. For each specialty, we calculated the number of practice sites per physician, geographic practice dispersion (median driving distance required to go to each practice site), and temporal practice dispersion (median travel time required to go to each practice site). We used linear regression to compare the number of practice sites, geographic practice dispersion, and temporal practice dispersion by specialty. Results: The number of physicians, mean number of practice sites, along with geographic and temporal practice dispersion by specialty are shown in the table. MO practiced at a smaller number of practice sites compared to GO (p<0.001) and RO (p<0.001). Compared to MO, SO had a smaller geographic dispersion (median driving distance 22 miles vs. 38 miles, p=<0.001) and temporal practice dispersion (median driving time 27 minutes vs. 43 minutes, p<0.001), whereas RO had a larger geographic dispersion (median RO driving distance 58 minutes, p<0.001) and temporal practice dispersion (median RO driving time 63 minutes, p<0.001). Conclusions: Oncologic specialties vary in the number of practice sites and practice dispersion per oncologist. In particular, GO and RO practice at more sites than MO, with MO practices more geographically concentrated than RO practices. While SO practice at a similar number of practice sites compared to MO, their practices are the most geographically concentrated. While these practice patterns may represent increased patient access to specialty oncology care, the impact on quality of care and physician wellness is unknown.[Table: see text]