Systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS) are defined genetically as complex diseases where multiple genes are involved in their pathogenesis. Among the genes of interest are those coding for the cytokines, molecules involved in immunoregulation that have been shown to play important roles in these diseases. Whether abnormalities in cytokine production are owing to genetic polymorphisms within the genes themselves is a matter of intensive study. The finding of functional polymorphisms within cytokine genes and their potential association with disease will open new avenues in their treatment.