Necrotizing sialometaplasia (NS) affects salivary glands, and despite being a benign condition, its clinical and histopathological features sometimes mimic other malignant pathologies of epithelial origin. This article presents two cases of NS and discusses clinicopathological features and the differential diagnosis of this condition. The first case, a 76-year-old woman with a 6-month history of painful oral thrush. Intraoral examination showed an ulcerative lesion located on the hard palate. The clinical hypothesis was squamous cell carcinoma. Second, a 26-year-old man with a 40-days ulcerative lesion on the soft palate. Intraoral examination revealed a reddish ulcer measuring 0.5 cm. Clinical hypothesis was traumatic ulcer. In both cases, a biopsy was performed, and a histopathological diagnosis of NS was established. NS cause is poorly understood, and its clinical features resemble other oral lesions with ulcerative aspects. Thus, dentists must be aware of the clinical features of oral ulcers with more than a 2-week duration without defined etiology.