The publication of two German systems of quality indicators for ambulatory care (AQUIK and QISA) in 2009 stimulated a discussion in German general practice about how to appropriately measure the quality of care in general practice / family medicine. The basic properties and requirements of quality indicators (QIs) in the international literature are discussed in terms of their ability to measure the specific processes of care in general practice. In the second part of the article the QISA system is presented as an example of a methodologically sound development of QIs for ambulatory care for use in both small practices and practice networks. In addition, the context of application and usage of QIs in primary care and the quality control they may provide are discussed. We conclude that important methodological problems have yet to be solved, particularly with measuring 'horizontal' dimensions of quality in primary care (such as comprehensiveness, co-ordination and person-centredness), but that the use of QIs may increase the visibility of general practice in Germany.