Background: Patients with malignancy suffer impairment of their quality of life (QoL). QoL has been evaluated in thyroid cancer patients. Since 2010, a new inventory, the thyroid-specific patient-reported outcome (ThyPRO) measure for benign thyroid disorders, has been available. Aim: This study evaluated QoL longitudinally in patients with a history of differentiated thyroid cancer (DTC) by means of the ThyPRO questionnaire. Methods : From 2012 to 2016, QoL was evaluated yearly in 123 adult DTC patients by means of ThyPRO. The ThyPRO questionnaire consists of 13 scales on which higher scores represent greater impact on QoL in areas affected by thyroid pathology. Disease-specific morbidity due to possible inadequate L-T4 treatment was evaluated by means of the Billewicz scale (BS). The same examinations were conducted in 192 control subjects who had undergone surgery for benign thyroid pathology. Results: DTC and control subjects had similar scores on all but one scale; scores on the hyperthyroid symptoms scale were significantly higher in DTC patients than in controls. Over the 5 years, scores did not change significantly in the DTC group. Overall, QoL and BS scores showed a slight, but not significant, improvement during the study period in DTC patients. BMI impacted on several ThyPRO scales. No significant differences between genders were noted in DTC. Conclusions: The ThyPRO questionnaire indicates that illness perception is similar after thyroidectomy for malign and benign pathology. Only a marginal improvement in QoL was noted in DTC subjects over the 5-year study period. In both groups, females showed a greater perception of illness than males.