Since Gruber first reported a case of bilateral submandibular gland(SMG) aplasia, about 30 cases of salivary gland aplasia have been reported. Most of these were the congenital absence of all major salivary glands. Unilateral aplasia of the SMG is an extremely rare that about 10 cases have been reported. It is presumed that the cause of congenital absence of salivary glands might be associated with ectodermal defects of the first and second branchial arches. The etiology of isolated absence of a major salivary gland without other anomalies is unclear. Recently, Koo et al and Luis et al reported 4 cases of isolated absence of a unilateral SMG accompanied with sialolith within the Wharton’s duct. It was suggested that in case of unilateral absence of submandibular gland, atrophy of the SMG resulting from recurrent sialadenitis with a previously formed sialolith might lead to this phenomenon. Here, we report 3 cases of unilateral absence of SMG detected with CT in our hospital. Additionally, with the aim of identifying correlation between sialolithiasis of SMG and atrophic change of the gland, we reviewed 750 cases of sialolithiasis of SMG patients treate in our hospital.