This retrospective study by the group from Proton Therapy Center, Czech, analyzed clinical outcomes of 853 patients with prostate cancer treated with an ultra-hypofractionated schedule (36.25 GyE/five fractions). There were 318 (37.3%), 314 (36.8%), and 221 (25.9%) patients at low (LR), favorable intermediate (F-IR), and unfavorable intermediate risk (U-IR). The whole group of patients reached median follow-up time at 62.7 months. Estimated 5-year biochemical disease-free survival (bDFS) rates were 96.5%, 93.7%, and 91.2% for low-, favorable intermediate-, and unfavorable intermediate-risk groups, respectively. Cumulative late toxicity of G2+ was as follows: gastrointestinal (GI)-G2: 9.1%; G3: 0.5%; genitourinary (GU)-G2: 4.3%, and no G3 toxicity was observed. PSA relapse was observed in 58 (6.8%) patients. The authors concluded that ultra-hypofractionated PBT is an effective treatment for low- and favorable intermediate-risk prostate cancer, with long-term bDFS rates comparable to other techniques, and it is promising for unfavorable intermediate-risk prostate cancer.