Population-based surveys have shown that health-related quality of life (HRQL) is influenced by patients' characteristics such as age, gender, living situation and diagnoses. The present study explores the impact of such factors on the HRQL of severely ill cancer patients. The study sample included 395 cancer patients who participated in a cluster randomised trial of palliative care. Median survival was 13 weeks. HRQL assessments (using the EORTC QLQ-C30 questionnaire) were compared among subgroups of relevant patients' characteristics (ANOVA), and the significance of individual covariates was explored by multivariate linear regression. Most EORTC QLQ-C30 scores showed minor differences between genders. Higher age was associated with less sleeping disturbance, less pain and better emotional functioning. No positive impact of living with a partner was found. Performance status and/or time from assessment to death were significantly associated with most functioning and symptom scores. We concluded that although the overall impact of sociodemographic characteristics may seem less important to HRQL scores among advanced cancer patients than in general populations, age and gender should be allowed for. Performance status and closeness to death also need to be reported.