Primary squamous cell carcinomas (SCC) of the salivary glands are localized predominantly in the major salivary glands and must be distinguished from metastases of extraglandular SCC of the skin, especially the head and neck area. Squamous cell metaplasia in non-tumourous diseases of the salivary gland (e.g. necrotizing sialometaplasia) as well as in benign or malignant salivary gland tumours (e.g. metaplastic Warthin tumour) can simulate SCC. Other differential diagnostic problems are the structural variants of SCC which develop predominantly in the minor salivary glands, but not in the major salivary glands. Special types include the very rare adenoid SCC with pseudoglandular structures as the result of acantholysis, the biphasic adenosquamous carcinoma with differentiation as SCC and adenocarcinoma, the biphasic basaloid squamous carcinoma with a structure as SCC and solid basaloid carcinoma (analogous to the solid type of adenoid-cystic carcinoma) and the poorly differentiated mucoepidermoid carcinoma (grade III) with biphasic structure of undifferentiated epidermoid and intermediate cells as well as inclusion of small groups of mucous-producing goblet cells. The differential diagnostic criteria are analysed concerning prognosis and treatment.