Radiographically guided fine-needle aspiration (X-FNA) in 215 nonpalpable, mammographically detected breast lesions was performed by means of a coordinate-grid localization system. Aspirates were categorized either into four cytologic groups or as simple cysts. Based on the most stringent cytologic criteria, the maximum sensitivity for detection of carcinoma was 97% and the specificity was 94%. However, according to these strict cytologic criteria, only 46% of aspirates contained representative material. Based on less stringent cytologic criteria, the maximum sensitivity was 68% and the specificity was 97%. Forty-one of 74 lesions proved to be malignant at biopsy. Thirty-four patients did not complete adequate mammographic follow-up. High sensitivity and specificity can be achieved with X-FNA. However, management decisions ultimately require integration of mammographic findings with cytologic results. Close cooperation among mammographer, surgeon, cytopathologist, and patient is mandatory for successful results.