Adiponectin is an abundant hormone secreted by adipocytes that exhibits anti-diabetic, anti-inflammatory and anti-atherogenic properties. However, in obesity, as adipocytes enlarge, adiponectin secretion declines. A sex dimorphism is observed in adiponectin levels with women having higher levels than men. We hypothesized that a lack of adiponectin negatively affects both insulin sensitivity and adipose physiology in a sex-dependent manner. In this study, male and female adiponectin knockout or wild-type mice were fed with either a low fat or high fat diet. Male knockout animals were more glucose intolerant and had elevated fasting glucose levels. In contrast, both adiponectin knockout and wild-type females showed decreased hepatic lipid accumulation on a high fat diet. In both sexes, lean adiponectin knockout mice had significantly smaller fat depot weights and lesser hepatic lipid accumulation than the lean wild-type mice. However, on high fat diet, only male adiponectin knockout mice had fat depot weights that were comparable to wild-type mice, which indicate a novel sex-specific role of adiponectin in determining adiposity.