Mycophenolic acid (MPA) is a selective inhibitor of inosine-monophosphate-dehydrogenase which leads to inhibition of the de novo pathway of nucleotide synthesis. The antiproliferative effect of MPA mainly affects activated T- and B-lymphocytes because the proliferation of these cells is critically dependent on the de novo purine synthesis compared to other eukaryotic cells. Since these lymphocytes have been suggested to play a pivotal role in the inflammation and immunopathogenesis of pSS, mycophenolate-sodium might be a promising agent in the treatment of pSS.