The aim of the present work was to evaluate the impact of xerostomia on the quality of life of patients who underwent radiotherapy in the head and neck region. This was a cross-sectional, quantitative study. The sample comprised 40 patients whose xerostomia was classified through the xerostomia inventory and the quality of life evaluated through the oral health impact profile questionnaire (OHIP). The majority of participants were male (75%), mean age 58.7 years. According to the degree of severity of the xerostomia, the average score among the participants was 36 points, this being considered moderate xerostomia. A significant impact was observed, with the median score 11 points, with the highest scores in the domains related to functional limitation, physical pain and physical disability. The majority of the participants (97.5%) had reduced salivary flow after the end of radiotherapy. There was a significant positive correlation between the degree of xerostomia and reduced quality of life, Pearson correlation 0.5421, (p< 0.05). Based upon the results it is concluded that xerostomia has a negative impact on the quality of life of patients who undergo radiotherapy in the head and neck region.