122 Abstract Background The aim of this prospective cohort study was to investigate swallowing function in relation to personal and clinical factors among patients with head and neck cancer (HNC) from diagnosis up to 2 years after treatment. Methods The 100 mL water swallow test was measured before treatment, and 3, 6, 12, and 24 months after treatment. Linear mixed-effects model analysis was conducted to investigate changes over time and the association with personal (sex, age) and clinical (tumor site, tumor stage, treatment modality) factors. Results Among 128 included patients, number of swallows increased from baseline to 3 months after treatment and decreased to baseline again at 6 months after treatment. The number of swallows was associated with age and treatment modality. Conclusion In patients with HNC, swallowing (dys)function changes over time with the worst score 3 months after treatment. A higher age and being treated with surgery are factors associated with swallowing dysfunction over time.