Objectives: To document the mammography data that are gathered by the organized screening programs participating in the International Breast Cancer Screening Network (IBSN), the nature of their procedures for data quality assurance, and the measures used to assess program performance and impact.

Methods: A detailed questionnaire covering multiple aspects of quality assurance in screening mammography was mailed to IBSN representatives in 23 countries.

Results: Countries collect a wealth of screening mammography data, much of it computerized. Most countries have designated staff for data quality assurance. All provide staff training, and most have documentation requirements for data collection. Nearly all have one or more procedures to maintain data confidentiality. Countries are heterogeneous in collecting and assessing data to monitor screening program performance and impact.

Conclusions: Demonstrating that population-based screening mammography reduces breast cancer mortality requires collection of high-quality data on key aspects of the multi-step screening process. Assuring the quality of data collection systems for screening mammography programs is an important and evolving area for IBSN countries.