In general, survival outcomes for patients with Head and Neck Cancer (HNC) has improved over recent decades. However, mortality within six months after diagnosis for curative patients remains at approximately 5%. The aim of this study was to identify risk factors for early death among patients with curative treatment, and furthermore, to analyze whether the risk of early death changed over recent years. This real-world, population-based, nationwide study from the Swedish Head and Neck Cancer Register (SweHNCR) included all patients ≥18 years diagnosed with HNC with a curative treatment intent at the multidisciplinary tumor board from 2008 to 2020. A total of 16,786 patients were included. During the study period a total of 618 (3.7%) patients with curative-intended treatment died within six months of diagnosis. Patients diagnosed between 2008 and 2012 had a six-month mortality rate of 4.7% compared to 2.5% for patients diagnosed between 2017 and 2020, indicating a risk reduction of 53% (p <0.001) for death within six months. The mean time to radiation therapy from diagnosis in the 2008-2012 cohort was 38 days, compared to 22 days for the 2017-2020 cohort, (p <0.001). The mean time to surgery from diagnosis was 22 days in 2008-2012, compared to 15 days for the 2017-2020 cohort, (p <0.001). Females had a 20% lower risk of dying within six months compared to males (p = 0.013). For every year older the patient was at diagnosis, a 4.8% (p <0.001) higher risk of dying within six months was observed. Patients with a WHO score of 1 had approximately 2.4-times greater risk of early death compared to WHO 0 patients (p <0.001). The risk of early death among WHO 4 patients was almost 28 times higher than for WHO 0 patients (p <0.001). Patients with a hypopharyngeal tumor site had a 2.5-fold higher risk of dying within six months from diagnosis compared to oropharyngeal tumor patients (p <0.001). We found that the risk of early death decreased significantly from 2008 to 2020. During this period, the mean time to the start of treatment was significantly reduced both for surgery and oncological treatment regimes. Among patients with a curative treatment intention, increased risk of early death was associated with male sex, older age, advanced disease, increased WHO score, and a hypopharyngeal tumor site.