Anti-Ro(SSA) and La(SSB) antibody determinations have become important serologic tests in the evaluation of lupus erythematosus and Sjögren's syndrome patients. These antibodies appear to identify a group of lupus patients with prominent skin diseases. Although much of the initial investigations regarding the value of these antibodies has been performed in the United States and Europe, preliminary studies suggest that the frequency of these antibodies in Japanese and other Oriental patients may be double that seen in American patients. This article will briefly review our knowledge of the molecular, immunogenetic and clinical features of the anti-Ro(SSA) and anti-La(SSB) antibody responses.