−866G/A polymorphism in the promoter of UCP2 gene has been reported to be associated with obesity, but the results remain inconclusive. To assess the relation of UCP2 −866G/A polymorphism and obesity susceptibility, a meta-analysis was performed. PubMed, ISI, Wanfang database, VIP and CBM were searched to identify relevant studies up to July 31, 2012. Odds ratios (OR) and 95% confidence interval (95% CI) were pooled using fixed or random effect models. Subgroup analysis was performed by ethnicity (categorized as Asian and European). Heterogeneity and publication bias evaluation were performed to validate the credibility. Meta-regression and the ‘leave one out’ sensitive analysis were used to explore the potential sources of between-study heterogeneity. 14 studies were included in this meta-analysis. After exclusion of articles that deviated from the HWE in controls, and were the key contributors to between-study heterogeneity, the meta-analysis showed a significant association of the A allele with reduced risk of obesity in overall analysis and in European in the dominant, codominant and additional models. In Asian, no significant association was found between the −866G/A in UCP2 gene and obesity susceptibility. The meta-analysis suggested that UCP2 −866G/A polymorphism was associated with obesity. The A allele may be an important protective factor for obesity in European, but not in Asian. Further studies are needed to elucidate the relationship.