Quality of life (QOL) has become an important outcome measure in the treatment of cancer patients. QOL mainly has been assessed in clinical trials within selective cancer populations to evaluate the effects of specific therapeutic procedures, whereas comparative analyses with QOL of population-based samples are rare. We assessed QOL one year after diagnosis in a population based cohort of 387 women with breast cancer from Saarland (Germany) using the EORTC-QLC30 questionnaire. Specific functional and symptom QOL-scores were compared with published reference data from the general population using indirect standardization and stratification on age. 373 out of 387 patients with breast cancer survived the first year after tumor diagnosis (96.4%). Of these, 314 returned the questionnaire (response rate: 84.2%). Breast cancer patients scored their social, cognitive and global health functioning only slightly worse than women of same age from the general population. More severe limitations among breast cancer patients were observed for the role and emotional functioning scales and for the symptom subscales insomnia and financial difficulties. Emotional, social, cognitive and role functioning scores of breast cancer patients tended to increase with age (indicating better performance among the elderly), whereas the physical functioning score declined. Age specific comparisons between breast cancer patients and the external reference population revealed that the differences were predominantly found in younger age groups. Deficits in role and emotional functioning and specific limitations like insomnia and financial difficulties are main factors hampering quality of life among breast cancer patients and seem to affect predominantly younger patients.