The MHC accounts for half of the genetic susceptibility to type 1 diabetes (T1D). Evidence suggests that an imbalance in Th1/Th2 responses may play a key role in the development of autoimmune diabetes. Since interleukin-10 (IL-10) modulates immune and inflammatory responses and has been implicated in many autoimmune diseases, it seemed interesting to examine whether IL-10 polymorphisms participate in diabetes predisposition. In fact, this is the first association study investigating the role of the IL- 10 polymorphisms in susceptibility to T1D in a Caucasian population. Three promoter polymorphisms (-1082G/A, -819C/T, -592C/A) and two CA-repeat microsatellites (IL-10R and IL-10G at -4 and -1.1 kb) were tested in a case-control study with 294 T1D patients and 574 healthy controls. Our results prove a minor role of IL-10 in the autoimmune diabetes risk, although we found the same association trend with IL-10G(*)12 allele as was previously observed for multiple sclerosis and rheumatoid arthritis.