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Most patients with p16-positive oropharynx cancer (p16+OPC) receive contralateral elective nodal radiation therapy that improves regional control but increases acute and long-term toxicity. We hypothesize a validated volume reduction in the contralateral neck is effective with an improved toxicity profile in patients with p16+OPC receiving definitive or adjuvant radiation therapy. Patients with newly diagnosed p16+OPC without contralateral nodal involvement treated with primary proton or photon-based (chemo)radiation or adjuvant (chemo)radiation following Transoral Robotic Surgery (TORS) were eligible for enrollment. The reduced contralateral nodal volume included regions of level II and III based on high risk locations for contralateral nodal disease. The primary endpoint was elective out-of-field contralateral nodal failure. Dosimetric comparisons between standard versus reduced elective nodal volumes were analyzed. Acute toxicity was collected using CTCAE v4.0. Fifty-two patients were enrolled of which 36 (69.2%) received definitive (chemo)radiation. Sixteen (30.8%) patients underwent adjuvant radiation following TORS of which 5 (31.2%) received concurrent platinum-based chemotherapy for high risk features. Proton therapy was used in 38 (73.1%) patients. There were no contralateral nodal failures at a median follow up of 15 months (range 1-24 months). For the first 20 patients enrolled, dosimetric comparison of the reduced contralateral elective nodal volumes to consensus elective nodal volumes demonstrated a decrease in the mean dose (18.5 Gy to 14.1 Gy [p<0.05]) and V30 Gy (21.3% to 11.6% [p<0.01]) of the contralateral parotid dose. Significant differences were independent of radiation modality or technology. Acute grade 3 toxicity was observed in 13 (25%) patients including 6 (11.5%) who received a PEG tube during treatment. There were no grade 4-5 acute toxicities, and at 6 months follow up no patients had retained a PEG tube. S elective a voidance of nodal v olum e s at minimal r isk in the N0 contralateral neck of patients with p16-positive oropharynx cancer can be safely performed while maintaining excellent regional control. Both dose to contralateral organs at risk and toxicities were favorable. Maturation of follow-up is ongoing to further support this de-intensification strategy. [ABSTRACT FROM AUTHOR]