Background: Engaging patients with advanced cancer in discussions about values and preferences in serious illness allows clinicians to deliver care that is consistent with their patients’ wishes and improves end-of-life outcomes. The COVID-19 pandemic necessitated serious illness conversations to occur via telehealth, yet little is known about how telehealth influences these conversations between patients and their oncology clinicians. Methods: We conducted a retrospective analysis of patients with metastatic lung cancer at a single academic center who had telehealth visits with their oncology clinicians. All outpatient and inpatient clinician notes for these patients were obtained from the electronic medical record during the first surge of COVID-19 in Massachusetts (03/10/2020 - 06/10/2020). Natural Language Processing (NLP) text identification software was used to conduct a semi-automated chart review and to identify documentation of discussion about five SIC domains (goals of care [GOC], limitation of life-sustaining treatment [LLST], prognostic awareness [PA], palliative care [PC] and hospice) and characterize the context of these conversations. We used unadjusted linear regression models to examine the relationship of SIC with (1) type of clinician (MD versus APP) (2) visit type (phone vs video), (3) cancer status, and (4) family involvement during the telehealth visit. Results: The study included 361 unique patients with 634 telehealth notes from 17 oncology clinicians. Most patients had non-small cell lung cancer (92%), and most telehealth notes were completed by physicians (88%). We identified 126 (34%) patients with documentation of discussion of at least one SIC domain. Of the 634 telehealth notes reviewed, 110 (17%) notes had documentation of one SIC domain while 78 notes (12%) documented two or more SIC domains. The most common SIC domain addressed was GOC (21%), followed by PA (16%). The domains of hospice (6%), PC (5%), and LLST (3%) were infrequently discussed. We found no association between clinician or visit type and SIC during telehealth visits. The presence of family at the visit (B=0.179, p=0.002) and progressive or newly diagnosed disease (B=0.58, p<0.001) were associated with an increased number SIC domains addressed during telehealth visits. Conclusions: During the COVID-19 pandemic, oncology clinicians used telehealth to conduct SIC in patients with advanced cancer, but this study demonstrated considerable heterogeneity in the content of these conversations. The presence of family at the visit and progressive or newly diagnosed disease were associated with an increased number SIC domains addressed during telehealth visits. Future efforts should focus on how to optimize telehealth tools to conduct these important conversations between patients and their oncology clinicians.