PCOS is a complex multifactorial disorder involving a number of genetic and environmental factors. One of the genetic factors that has been associated with PCOS is Interleukin 1 beta (IL-1β), is an important inflammatory cytokine that plays a regulatory role in both the body's immune and the inflammatory responses. All these responses appear to be are also affected in at least some women with PCOS. To investigate the possible association of polymorphisms of the IL-1β gene with the occurrence and clinical characteristics of PCOS, we evaluated two common polymorphisms of the IL-1β gene (promoter C [-511] T and exon 5 position [+3953]) in 200 Chinese women with PCOS and 177 healthy Chinese controls. We found the frequency of IL-1β C/C [-511] genotype in PCOS was significantly higher than that in the controls (χ(2) = 15.48, df = 1, P < 0.001 OR = 2.73 95% CI: 1.64-4.56 by genotype; χ(2) = 10.21, df = 1, P = 0.001 by allele). However in contrast, no association between genotype and relative allele frequencies was observed for the C [+3953] T polymorphism for Chinese women with PCOS when compared to that for a similar group of Chinese women without PCOS (P = 0.35).