ABSTRACT: Importance:In recent years, transoral robotic surgery (TORS) has emerged as a useful treatment for oropharyngeal squamous cell carcinoma (OPSCC). In appropriately selected patients, the use of TORS may allow avoidance of adjuvant chemotherapy and/or radiotherapy, thereby avoiding the long-term adverse effects of these therapies. Objective:To compare functional speech, swallowing, and quality-of-life outcomes longitudinally between those undergoing TORS only and those undergoing TORS and adjuvant radiotherapy (TORS+RT) or TORS and chemoradiotherapy (TORS+CRT). Design, Setting, and Participants:This prospective, longitudinal cohort study performed from June 1, 2013, through November 31, 2015, included 74 patients undergoing TORS for initial treatment of OPSCC at a single tertiary academic hospital. Main Outcomes and Measures:Data were collected at baseline, postoperatively (7-21 days), at short-term follow-up (6-12 months), and at long-term follow-up (>12 months). The quality-of-life metrics included the 10-item Eating Assessment Tool and the University of Michigan Head and Neck Quality of Life instrument. Data were also collected on tumor staging, surgical and adjuvant therapy details, patient comorbidities, tracheostomy and feeding tube use, and functional speech and swallowing status using the Performance Status Scale for Head and Neck Cancer Patients. Results:Seventy-four patients were enrolled in the study (mean [SD] age, 61.39 [7.99] years; 68 [92%] male). Median long-term follow-up was 21 months (range, 12-36 months). The response rates were 86% (n?=?64) postoperatively, 88% (n?=?65) at short-term follow-up, and 86% (n?=?64) at long-term follow-up. In all 3 groups, there was a significant worsening in pain and all swallowing-related measures postoperatively. There was subsequent improvement over time, with different trajectories observed across the 3 intervention groups. Postoperative dysphagia improved significantly more quickly in the TORS-only group. At long-term follow-up, weight loss differed between the TORS-only and TORS+RT groups (mean difference, -16.1; 97.5% CI, -29.8 to -2.4) and the TORS-only and TORS+CRT groups (mean difference, -14.6; 97.5% CI, -29.2 to 0) in a clinically meaningful way. In addition, the TORS-only group had significantly better scores than the TORS+CRT group on the Performance Status Scale-Eating in Public scale (mean difference, 21.8; 97.5% CI, 4.3-39.2) and Head and Neck Quality of Life-Eating scale (mean difference, 21.2; 97.5% CI, 4.0-38.3). Conclusions and Relevance:Patients who underwent TORS+CRT demonstrated poorer long-term outcomes, with continued dysphagia more than 1 year after surgery. These findings support the investigation of adjuvant de-escalation therapies to reduce the long-term adverse effects of treatment.