Osteoporosis is a common disease in the aging population and studies have shown that interleukin-6 (IL-6) is potentially implicated in its pathogenesis. This study was designed to assess the association between the IL-6 gene -634C/G polymorphism and osteoporosis. PubMed, Embase, China National Knowledge Infrastructure, and Wanfang databases were searched for eligible studies published up to and including December 2014 in English or Chinese. Meta-analysis was conducted by the RevMan5.2 software. Weighted mean difference and 95% confidence interval (95%CI) were calculated by a fixed-effect or random-effect model. Bone mineral density (BMD) was regarded as the assessment index. As a result, a total of four articles with 3068 subjects were included. Differences in BMD between the CC and GG genotypes were 0.03 g/cm(2) (95%CI = 0.01 to 0.05) at total body, 0.01 g/cm(2) (95%CI = 0.00 to 0.03) at femoral neck, and 0.03 g/cm(2) (95%CI = 0.00 to 0.06) at the lumbar spine (P < 0.05). For the CG versus GG genotypes, the differences in BMD were 0.03 g/cm(2) (95%CI = 0.02 to 0.05) at total body and 0.02 g/cm(2) (95%CI = 0.00 to 0.03 at the femoral neck (P < 0.05). For the CC versus CG genotypes, the differences in BMD were not significant (P > 0.05). In conclusion, the GG genotype of the -634C/G polymorphism in IL-6 appears to play a role in reducing BMD, which affects normal bone metabolism and leads to osteoporosis.