Swelling of the salivary glands is often an initial sign of immunoglobulin G4 (IgG4)-related disease or IgG4-related sclerosing/autoimmune disease. We encountered 2 patients with IgG4-related disease who showed swollen submandibular glands with a unique characteristic sonographic pattern. Bilateral submandibular glands of both patients were enlarged with a smooth contour. The internal echo texture indicated multiple hypoechoic foci scattered against a heterogeneous background, which characteristically appeared with a mottled or irregular netlike appearance. A histopathologic examination of a resected section showed multiple foci of dense infiltrated lymphoplasmacytic cells and lymph follicles encircled by fibrous bands. A mottled appearance in the sonographic findings of the submandibular glands suggests the characteristic of IgG4-related disease and can be helpful in the differential diagnosis at the initial manifestation.