INTRODUCTION: In the year 2000 a quality assurance programme for the preoperative breast diagnostics was introduced in Denmark. The programme was based on the "European guidelines for quality assurance in breast cancer screening and diagnosis" where - among other measures - five cytological diagnostic classes were introduced. The aim of this study was to evaluate the quality assurance programme in a screening population to determine whether fine needle aspiration cytology (FNAC) as first choice remains a useful tool in the preoperative diagnostics, or if needle core biopsy should be the first-choice treatment. MATERIAL AND METHODS: 767 women had FNAC performed from a total of 783 lesions at the Mammography Clinic, University Hospital Odense. All FNACs were compared with the final histology diagnosis. Nine statistical parameters were calculated according to the European guidelines. RESULTS: A total of 66% of the 783 FNACs had a malignant cytology diagnosis, which in 99% of the cases turned out to be the correct diagnosis. Four lesions were false positives all of which represented benign proliferative breast diseases. The surgical procedures in these cases were either excisional biopsy or lumpectomy. The values of eight of the nine mutually dependent statistical parameters of quality scored within the recommended threshold values. Specificity was the only parameter that fell outside the recommended threshold values. CONCLUSION: Although specificity in our study is lower than recommended, we find that the use of FNAC as first-choice in triple diagnostics is a useful tool.