The object of this study was to investigate how the information status with regard to diagnosis, in addition to social and clinical factors, influenced emotional functioning and quality of life in a group of cancer patients in Turkey. A consecutive sample of 100 cancer patients being treated for different diagnoses in a tertiary care centre were prospectively evaluated. Data on patient disease and social characteristics, clinical factors, and scores on the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) were analysed by logistic regression models. A significant proportion (44%) of the patients did not know of their diagnosis of cancer. The scores on functional and symptom scales and global health status/quality of life according to QLQ-C30 did not differ according to the information given or not given on diagnosis. However, the independently significant determinants of good emotional functioning were male gender (P=0.002), low serum alanine transferase levels (P=0.025), good social functioning (P=0.002), and the absence of constipation (P=0.005). In Turkey, it is still common for cancer patients not to be informed of their diagnosis, and there is a great need to improve this situation. Honest disclosure of the truth does not worsen any dimension of quality of life in general or emotional functioning in particular. On the contrary, those with hepatic dysfunction, female gender, poor social functioning and constipation are the ones at increased risk of poor emotional functioning, and these patients may benefit from psychological screening.