Enhanced secretion of anti-inflammatory Th2 cytokines is a characteristic feature in normal physiological pregnancy. In recurrent spontaneous abortions (RSA), however, defective production of interleukin-10 (IL-10) and other Th2 cytokines has been shown in humans. Association studies have shown that a base exchange polymorphism (guanine-->adenine) at position -1082 of the IL-10 promoter is associated with differential IL-10 production. Since factors contributing to IL-10 production appear to be important in RSA, we studied the IL-10 genotypes of 38 Finnish women with a history of three or more consecutive abortions and 131 ethnically matched healthy controls. No significant differences in the -1082 allele or genotype frequencies were found between the controls and the RSA women. The present study suggests that the IL-10 -1082 (G-->A) polymorphism is not a major genetic regulator in RSA.