A wide variety of masses in the head and neck, including those in the major salivary glands, can be approached by fine needle aspiration. In many instances, a correct definitive diagnosis con be rendered after examination of smears or cell block material. However, several significant but uncommon areas can lead to diagnostic difficulties, with the potential for clinically important diagnostic errors. Many of these occur in salivary gland lesions. The most frequent problems involve variations in the expected cytology of pleomorphic adenoma. Then, there are several benign-malignant "look-alike" pairs of lesions. The first of these is related to small-cell epithelial neoplasms of low nuclear grade; the most frequent problem is between basal cell adenomas and adenoid cystic carcinoma, particularly the solid (anaplastic) type. The next area contrasts mucoepidermoid carcinoma with its cytologic mimic, benign salivary gland duct obstruction. The final difficulty in salivary gland aspiration contrasts large-cell epithelial lesions of low nuclear grade: oncocytic proliferations and acinic cell carcinoma. The clinical implications of cytologically benign squamous cell-containing cyst aspirates from the lateral neck will be discussed. Finally, a brief consideration of methodological optimization for thyroid aspirations will be offered.