A program for mammography optimization in individual x-ray units, named Dose and Quality in Mammography (DQM), is now underway in Italy. The project has three stages: measurement of the parameters that affect dose and image quality by means of devices that are practical to use (specifically designed for the purpose), analysis of data to evaluate dose and image quality and suggestion of possible improvements to each unit operator. Instruments and methods employed in our survey are described. Our results, like those of the American survey (Je78) Breast Exposure: Nationwide Trends (BENT), show widespread variations of exposure, half value layer (HVL), optical density, dose and resolution. Facilities using the same type of x-ray apparatus (Mo target-Mo filter) and film-screen combinations present very different exposure values, ranging from 1.6 X 10(-4) to 27.6 X 10(-4) C kg-1. The causes of these variations--ascribable to the individual units, radiologist preferences, processing condition, kVp indicator and timer accuracy--are being explored.