Core needle biopsy is a preferable breast biopsy technique under ultrasound guidance. However, fine-needle biopsy is considered equally popular. To redefine the role of fine-needle aspiration biopsy (FNAB) in the diagnosis of breast lesions. We retrospectively analysed the medical records of 680 patients who underwent breast ultrasound examination. In most cases, no pathologic structures were observed within the mammary glands. In 321 patients, the presence of focal lesions was revealed, and 107 patients in this group qualified for FNAB according to current recommendations. Patients with suspicious smears were referred for core needle or surgical biopsy. Patients with benign cytological smears underwent repeated ultrasound checks at 6-month intervals during the following year. All the smears were diagnostic. The vast majority of the results were categorised as benign lesions. Cancer cells were detected in six women. In one patient the lesion was classified as suspicious, probably malignant. In all of these cases, open biopsy was performed, and histopathological examination confirmed the presence of a malignant tumour. The patients were given appropriate oncological treatment. For women with benign or suspicious, but probably benign, lesions, breast ultrasound was performed twice at six-month intervals. Control tests showed no significant changes compared to the baseline examination. None of the patients required extensive additional diagnostic tests. FNAB is a reliable method of assessing pathologic lesions in mammary glands.