OBJECTIVES: Since September 2015, filgrastim-sndz (FIL-SNDZ), a biosimilar of filgrastim (FIL), has been available in the United States (US) at approximately a 15% discounted price compared with FIL. FIL-SNDZ is approved for 5 out of 6 FIL indications, and is listed among the recommended granulocyte colony-stimulating factors (G-CSFs) in the American Society of Clinical Oncology (ASCO) clinical practice guidelines for prevention of treatment-related febrile neutropenia in patients with solid tumor or lymphoma receiving chemotherapy. Our objective was to identify physician documentation and utilization of FIL-SNDZ during patient office visits, and compare FIL-SNDZ use with other G-CSFs. METHODS:  Physician records were extracted from January 1, 2016 through December 31, 2016 from RealHealthData, a US nationwide medical transcription database providing data within 72 hours of each patient visit to a participating provider. Records were searched for mention of FIL-SNDZ, tbo-filgrastim (TBO-FIL), FIL, and pegfilgrastim (PEG), then counts were tabulated to identify the most common location (US state) and medical specialty of the providers. Counts will be refreshed in May 2017. RESULTS:  Counts of each mentioned G-CSF, unique patients, and most frequent provider type and state were: FIL-SNDZ: 72 (33 patients), general practitioner, Kansas; TBO-FIL: 1136 (420 patients), multispecialty, Texas; FIL: 4149 (2347 patients), general practitioner, Texas; PEG: 6496 (3391 patients), general practitioner, Pennsylvania. Most G-CSF mentions originated from general practitioners in Texas, Pennsylvania, and Virginia. CONCLUSIONS:  Among 11,853 records reporting a G-CSF, only 72 mentions (0.6%) of FIL-SNDZ occurred in the 15 months since entry into the US marketplace. Although provider type was similar, the current data underline the geographic disparity in utilization of FIL-SNDZ from that of other G-CSFs. The May 2017 update will confirm whether FIL-SNDZ utilization has increased, as is anticipated with growing awareness and understanding of biosimilars among US clinicians and payers.