Radiotherapy (RT) for head and neck cancers causes salivary dysfunction and diminished xerostomia-related quality of life. We have demonstrated that three-dimensional treatment planning and conformational dose-delivery techniques can minimize RT doses to contralateral parotid glands while providing therapeutic doses to tumors. This study's purpose was to assess parotid salivary function up to 1 year post-RT in patients receiving bilateral neck parotid-sparing RT, and to determine if parotid preservation would significantly improve xerostomia-related quality of life. Unstimulated (UPFR) and stimulated (SPFR) parotid flow rates were collected from 20 head and neck cancer patients. All subjects completed a 15-item xerostomia-related quality of life scale (XeQoLS) prior to RT, at the completion of RT, 1, 3, 6 and 12 months post-RT. Salivary flow rates from spared and treated glands were significantly decreased at the completion of RT. After RT completion, spared UPFR and SPFR function increased and was not significantly different from baseline values. Output from treated glands remained statistically indistinguishable from zero throughout the post-RT period. Subjects had a significantly worse xerostomia-related quality of life at the completion of RT compared to baseline, and XeQoLS responses improved significantly 1 month post-RT. Responses at 1 year were markedly better than at the completion of RT, but still significantly worse than baseline. These findings suggest that despite parotid-sparing RT, salivary flow rates from treated and spared glands and xerostomia-related quality of life decrease at the completion of RT. However, with the use of parotid-sparing RT, contralateral glands are preserved at 1 year post-RT with a concomitant improvement in xerostomia-related quality of life.