Objective: The aim of the present study is to evaluate the significance of the fine needle aspiration biopsy (FNAB) compared to the histological diagnosis and to compare the reliability of the X-ray mammography versus the reliability of ultrasonic mammographic examination of the breast. Methods: The material was collected during 1992 and 1993, a total of 2964 breast examinations were performed. The X-ray mammography was performed in 1711 patients and was the only examination in 565 cases. The US breast examination was performed as the only examination in 1253 cases and both the X-ray mammography and the US breast examination were performed in 1146 patients. The total number of FNAB performed was 855 and in 85 cases the samples from the breast masses or the structural changes were reported as Papa-classes III-V and needed surgical evaluation. An additional three cases needed surgical evaluation, the samples were reported as Papa-class II and the cytologist recommended a histological diagnosis. Among these 88 cases 76 breast cancers were found. Results: In the present material the sensitivity of mammography was 75% and the sensitivity of US examination 100%. The sensitivity of FNAB was 90% with no false negative cytological result in the group of the operated patients. One false positive report (1.3%) was given and in the cases reported as Papa-classes III-IV 42% of the lesions were benign. A malignant tumor was found in 87% of the operated patients. This study revealed that a breast cancer ∼ 60% in diameter smaller could be evaluated on the ultrasound breast examination than on the X-ray mammography. It could also be possible to visualize a breast cancer on the ultrasound mammography several years before doing so on X-ray mammography. The cost of diagnosing and treating a breast cancer patient was 8640 USD. Conclusion: According to the results of this study, the US breast examination seems to be the best method for diagnosing breast cancer.