Background: The QUADAS tool was developed 2003 and validated 2006. As generic instrument for diagnostic accuracy studies it was developed with an option to amend/modify items for specific topics. For a guideline update on early diagnosis of breast cancer an evidence-report of trials concerning double-reading of screening-mammograms or breast-ultrasound after negative screening-mammogram was done. Objectives: To assess the quality of screening studies for double-reading of mammograms or breast-ultrasound after negative mammogram using the QUADAS tool. Methods: Studies were identified through a systematic literature search. For quality appraisal QUADAS was applied. It consists of 14 questions (to be answered ‘yes’, ‘no’ or ‘unclear’) addressing patients representativeness (n = 2), bias (n = 9) and quality of reporting (n = 3). Results: 22 Studies were assessed (14 DR, 6 US). Patients representativeness was poor for US studies (50%) but not for DR-studies (100%). The most critical issue for bias was verification of test results by a reference standard (0% US, 13,6% DR). Use of the same reference standard regardless to index test result (0%) and short time period between index test and reference standard (0%) seemed not applicable to the present interval-screening studies. Quality of reporting was high for the index test (83% US, 100% DR), but for US-studies not for the reference test (50%). Criteria not explicitly addressed by QUADAS was the use of standard diagnostic criteria (64% DR, 16,6% US) and clinical endpoints. Clinical endpoints used were cancer detection and recall rate. None of the studies verified the impact on breast cancer mortality. Quality of endpoints was classified as not sufficient. Conclusions: The quality of the analyzed studies was poor or limited for various aspects. For screening studies, clinical endpoints should be considered in quality appraisal. Not all QUADAS questions were applicable. Use of standard diagnostic criteria should be claimed for study assessment in general.