Cystic lesions of the parotid gland may be the presenting symptom in human immunodeficiency virus (HIV)-positive patients. The most common lesion is the benign lymphoepithelial cyst. Malignant lesions may also be associated with-or be hidden by-a cystic mass. We report a case of mucoepidermoid carcinoma in a 40-year-old HIV-positive woman who presented with a large cystic mass of the parotid that had been previously misdiagnosed as benign on several fine-needle aspiration biopsies. On our histologic examination, the true pathologic nature of the lesion was revealed. We suggest that an image-guided fine-needle aspiration biopsy of the thickened wall of cystic masses of the parotid may be more diagnostic than a random sampling of the contents.