Salivary gland ultrasonography (US) has recently been re-discovered as a useful tool to assess salivary gland involvement in primary Sjögren's syndrome (SS). In this review, we discuss US of the major salivary glands in the diagnosis of primary SS and analyse the possible added value of inclusion in classification criteria. We review the literature concerning associations between US of the major salivary glands, salivary gland histology and serology, with the possibility that US may be of value in disease stratification. We also examine the possible utility for US to monitor patient response to therapy in both clinical research and standard clinical care.