Background: We investigated the effects of intensity-modulated radiotherapy (IMRT) on xerostomia, quality of life (QoL) and protection of the parotid glands in patients with nasopharyngeal carcinoma (NPC) compared to three-dimensional conformal radiotherapy (3D-CRT).Methods: Eighty patients with NPC were enrolled in a prospective randomized clinical study and received IMRT or 3D-CRT. A xerostomia questionnaire (XQ), QoL questionnaire and parotid gland function assessment were completed at baseline and 6 months after radiotherapy.Results: Xerostomia occurred in both groups after RT, although the XQ scores of the IMRT group were lower and, as a consequence, the QoL scores were higher than in the 3D-CRT group. A correlation analysis showed that there was some correlation between the XQ and QoL scores. After 6 months of RT, the uptake index (UI) and excretion index (EI) decreased by 34.41% and 22.66% in the IMRT group, while in the 3D-CRT group the UI and EI decreased by 54.4% and 41.9%, respectively, and the function of the parotid glands declined. Conclusions: IMRT better relieved xerostomia and improved the QoL of NPC patients by sparing the parotid glands, without compromising treatment of the target site.