There has been increasing emphasis in research on understanding how cancer impacts an individual's quality of life (QOL) . The purpose of this study was to determine the levels of psychological distress and examine how this correlates with QOL in cancer patients. A total of 669 patients completed both the European Organization for Research and Treatment of Cancer (EORTC) Quality-of-Life Questionnaire C30 (QLQ-C30) and the Hospital Anxiety and Depression Scale (HADS) . The association between the patients' HADS scores and their emotional function scorings was analyzed by multiple linear regression analysis. Predictors of selected dimensions of QLQ-C30 were analyzed by multiple linear regression, where the patients' HADS and demographic and medical variables were included as explanatory variables. A statistically significant correlation was found between the emotional function score of QLQ-C30 and HADS-A (anxiety) and HADS-D (depression), respectively, with the highest correlation coefficient for HADS-A. However, HADS-D was significantly more related to other QOL dimensions than HADS-A, and depression was more highly correlated with reduced QOL than anxiety. Demographic and medical variables also influenced the correlation between HADS and selected dimensions of QLQ-C30. The emotional function dimension of QLQ-C30 predominantly assessed anxiety, but depression had a stronger impact on overall QOL of patients than anxiety. Therefore, additional measures are recommended to assess depression in cancer patients. Furthermore, demographic and medical variables should be assessed simultaneously to identify patients with impaired QOL.