To determine the role of transforming growth factor beta 1 (TGFbeta1) gene polymorphisms in the pathogenesis of systemic lupus erythematosus (SLE), we investigated the polymorphisms of T869C of the TGFbeta1 gene in 196 patients with SLE and 106 healthy controls by analyzing polymerase chain reaction-restriction fragment length polymorphism. The genotype and allele frequencies of T869C of the TGFbeta1 gene did not differ between SLE and healthy controls. However, compared to the TC and CC genotypes, the TT genotype was associated with anti-SS-A/Ro antibody production (p=0.029) and a higher incidence of aseptic necrosis (p=0.0097); the CC genotype had a higher frequency of anti-RNP antibody production compared to the patients with the TC and TT genotypes (p=0.023). These results suggest that T869C polymorphism of the TGFbeta1 gene is involved in the development of autoantibodies and the occurrence of aseptic necrosis in patients with SLE. Thus, TGFbeta1 polymorphism might be one of the genetic factors that explain the heterogeneity seen with SLE.