The interleukin-6 genotype (IL6 -174GG) has been proposed to be associated with sudden infant death syndrome (SIDS). The aim of this study was to investigate the -174G/C polymorphism in 175 Norwegian SIDS cases and 71 controls. There were no differences in genotype distribution between these two groups (p = 1.0). This confirms the findings in a combined SIDS group compared with European Caucasian controls, but not findings in smaller cohorts of SIDS cases from Australia and England. The discrepancy may result from bias introduced when investigating only a few SIDS cases, differences in diagnostic criteria when diagnosing the cause of death as SIDS, and differences in the distribution of the -174G/C polymorphism in different ethnic groups. Findings of an activated immune system in SIDS indicate that genes involved in the immune response are of importance. However, because there are several polymorphisms in the IL6 gene promoter that could potentially regulate the expression of the gene, more than one polymorphism should be investigated to assess the involvement of the IL-6 gene in SIDS.