Objective. Cancer and its treatment have an influence on health-related quality of life (HRQOL). Normative data could help to interpret HRQOL among cancer patients. Our aim was to generate longitudinal normative data based on sex, age and morbidity for the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 questionnaire. Methods. The QLQ-C30 and the Self-administered Comorbidity Questionnaire were administered to a representative panel of the Dutch-speaking population in the Netherlands in 2009 (n = 1743), 2010 (n = 2050), 2011 (n = 2040), 2012 (n = 2194) and 2013 (n = 2333). Results. Regarding sex, at baseline, women scored statistically significant and clinically relevant worse on fatigue, pain and insomnia compared to men. Regarding age groups and sex, HRQoL was lower among the older age groups in men and women. For men, at baseline, significant and clinically relevant age differences were found on physical, role and cognitive functioning, global QOL scale, fatigue, pain and dyspnea. The change over 5 years was larger for older age groups. For women, at baseline, significant and clinically relevant age differences were found on physical functioning, role functioning, nausea/vomiting, pain, dyspnea and insomnia. Those without self-reported morbidities reported a better HRQoL compared to those with morbidities. Among those who completed five assessments, the summary scale scores were stable over time, were higher in men than in women, and higher in younger compared to older age groups. Conclusions. Although HRQoL remains relatively stable over time, HRQoL data needs to be interpreted with care as many confounding factors can have an impact on HRQOL. Our data (which is freely available) can aid in the interpretation of QLQ-C30 scores and can help increase our understanding of the influence of age, sex, time and morbid conditions on HRQoL among cancer patients.