Background: With the growing complexity and cost of cancer care, adoption of oncology pathway tools as clinical decision support (CDS) has increased at the point of care. These tools have been shown to improve care quality, reduce variations in care and reduce healthcare costs. Flatiron Assist (FA) is a customizable CDS tool that is embedded in the electronic health record (EHR) to facilitate selection and documentation of National Comprehensive Cancer Network (NCCN) guideline concordant cancer treatment regimens. The time burden of engaging with CDS tools is a top concern for clinicians and often limits uptake of these tools. However, data on the actual time spent utilizing these tools in clinical practice is limited. Our study reports on the time spent by clinicians in various oncology practices, utilizing and ordering cancer treatment regimens with a CDS tool. Methods: We reviewed all completed sessions in FA from July 23, 2021 to May 23, 2022 by 878 prescribers at 24 academic and community oncology centers. Sessions that were part of an electronic prior authorization pilot program were excluded for purposes of standardization. Session length was defined as the time from the completion of application launch to application exit. For prescribers who completed over 20 sessions, we compared the mean sessions lengths of user’s initial sessions (#1-10) to subsequent sessions (#11-20) using paired t tests. We also determined the total number of potential CDS tool sessions per user per week. Results: All 14,394 CDS tool sessions were analyzed during the 10 month observation period. Median session length was 42 seconds (95th percentile, 253 seconds or 4.2 minutes). The average number of treatment orders placed was 5 per week per provider. Table shows the median session length across the 9 most commonly treated cancers. For the 31 prescribers who started using FA during the study and completed more than 20 sessions, the mean (SD) session length decreased from 95.2 (11.8) seconds in sessions #1-10 to 71.0 (6.0) seconds in sessions #11-20 (two-sided P = 0.034). Conclusions: Utilization of FA as a CDS tool to provide guideline concordant care is feasible and adds less than 4 minutes/week on average to a provider’s workflow. When used effectively, it can integrate seamlessly into provider workflows across academic and community practices without disruptive increases in time or effort of cancer treatment regimen ordering. Future studies are needed to evaluate the impact of product improvements, content changes, and electronic prior authorization integrations on time in this workflow.