Abstract: Described is a method for diagnosing a person having or being at risk of developing Sjögren's Syndrome and excluding patients with symptoms similar to Sjögren's Syndrome but with a different etiology, comprising the following steps: providing a sample of a body fluid or tissue from said person, said sample containing a mixture of unknown proteins, protein fragments or peptides; analyzing said samples with mass spectrometry to generate a m/z (mass to charge ratio) spectrogram for each sample; comparing whether the patient's sample contains m/z values that are characteristic of a Sjögren's Syndrome reference database derived from the analysis and cataloguing of multiple patient spectrograms; and determining whether said patient either has or does not have Sjögren's Syndrome on the basis of this comparative analysis.