This study presented efficacy and toxicity outcomes among 100 patients with chordoma treated on the Proton Collaborative Group prospective registry. Locations included base of skull (61%), spine (23%), and sacrum (16%). The median total dose was 74 GyRBE using PS-PBT (13%), US-PBT (54%) and PBS-PBT (33%). The 2/3-year LC, PFS, and OS rates are 97%/94%, 89%/74%, and 89%/83%, respectively. Eight patients experienced acute grade 3 toxicities, most commonly pain (n=3), radiation dermatitis (n=2), fatigue (n=1), insomnia (n=1) and dizziness (n=1). No grade ≥4 acute toxicity nor grade ≥3 late toxicities were reported. The conclusion of this study is that PBT achieved excellent safety and efficacy outcomes with very low rates of treatment failure. CNS necrosis is exceedingly low (<1%) despite the high doses of PBT delivered.