A pilot study of breast dose measurements on two mammography units in Bulgaria was conducted. The mean glandular doses (MGDs) to samples of approximately 60 women per unit were measured. MGD with a standard PMMA phantom was measured as well. The MGDs were calculated according to the European protocol on dosimetry in mammography as well as to the European protocol for the quality control of the physical and technical aspects of mammography screening. The measured women's MGDs were divided into three groups depending on the compressed breast thicknesses. The results for the group of thicknesses in the interval 40-60 mm were compared with the results from the measurements on the standard 45 mm PMMA phantom. Some differences were found which could be due to errors in breast thickness measurements, differences in breast and phantom densities and other factors. A standardized procedure was elaborated for patient dose measurement and calculation both from patient and phantom studies.