Adenoid cystic carcinoma is a rare valiant of mammary cancer with better prognosis. The diagnosis is usually made by histologic examination of biopsy specimen. Recently, we have experienced a case of adenoid cystlc carcinoma initially diagnosed by fine needle aspiration cytology which revealed distinct cytologic features in a 45-year-old woman. Pink to red globules in the tumor cell clusters on Diff-Quik staining was a very helpful finding for cytologic diagnosis.