(1) Background: The goal of the study was to evaluate psychological tolerance and health-related quality of life (QOL) in head and neck (HN) cancer patients treated with definitive accelerated radiotherapy (DART); (2) Methods: Seventy-six recurrence-free patients eligible for the study, who were treated with DART in the CAIR-2 phase III clinical study (median of follow-up=47 months), completed EORTC QLQ-C30 with H&N35 module, Hospital Anxiety and Depression Scale (HADS) and Visual–Analog Scales (VAS) of pain in HN and the neck / arm area.; (3) Results: The most dominating symptoms measured with QLQ-C30 were: fatigue (44/100), sleeplessness (39/100), financial problems (38/100) and pain (32/100). Within H&N35 the highest scores were reported on the subscales of sticky saliva (60/100), mouth dryness (65/100) and increased intake of painkillers (50/100). Pain (VAS) was reported by 87% (HN area) and 78% (shoulder) of the patients, with a mean score of 3/10. One-third reported depressive mood (HADS≥15 points) with an average score of 12.5/42 p. The depressed group, who smoked more as compared to non-depressed before DART (96% vs 78%) and required steroids treatment (85% vs 58%) during DART, also scored significantly worse on 23 of 35 subscales of QLQ-C30 and H&N35 and experienced more intense pain (VAS). Women, and less advanced patients scored better in several aspects of the quality of life; (4) Conclusions: Patients treated with DART struggle with low quality of life and persisting treatment-related symptoms including constant pain. HNC survivors, especially those, who are depressed, may require additional psychosocial, rehabilitation and medical intervention programs..