Passive smoking has decreased in recent years ("increased hygiene"). Less environmental tobacco smoke (ETS) gives increased hygiene that, if the hygiene hypothesis is true, in turn might give more autoimmune diseases. The presence of auto antibodies is considered to be an early indicator of type 1 diabetes (T1D). Because tobacco exposure may influence the immune system, we analyzed the relation between passive smoking and development of autoantibodies. A subsample (n= 8794) of the children in the ABIS study was used for this analysis. The parents answered questionnaires on smoking from pregnancy and onwards, and blood samples from the children aged 2.5-3 years were analyzed for GADA and IA-2A. Results showed that there was no significant difference in the prevalence of GADA or IA-2A (>95 percentile) between tobacco-exposed and nonexposed children. It was concluded that passive smoking does not seem to influence development of diabetes-related autoantibodies early in life.