We report a case of acinic cell carcinoma of the parotid gland. A 33-year-old man noticing a slow-growing mass in the right parotid gland was found in fine-needle aspiration to have abundant epithelial cells with little atypia. Although rich cellularity suggested a neoplastic nature, other cytological clues for specific diagnosis were not seen. The resected tumor was histologically acinic cell carcinoma. With this histological diagnosis, reviewing the FNA specimens indicated that, in the cases of low-grade cancer, cellular atypia were of little help as diagnostic clues. Detailed knowledge of histological subtypes of acinic cell carcinoma appears to be essential for accurate cytological diagnosis.