The diagnostic approach to Sjögren's syndrome (SS) is devoted to the assessment of glandular and extraglandular features of the disorder. Although this syndrome has been attracting growing interest from many investigators in the last few decades, complete agreement on the diagnostic tools to be used for this syndrome has not yet been reached. Finding a rational diagnostic approach to Sjögren's syndrome is even further complicated by the fact that this disease may exist alone, or in association with a number of extraglandular systemic manifestations or a well-defined systemic autoimmune disease. In this paper the entire matter has been critically reviewed in order to evidentiate the differences among the various diagnostic procedures proposed by different authors and to underline the need for a uniform classification criteria for SS.