Background: Cord blood (CB) leptin is positively associated with adiposity at birth, but the association with child adiposity is unclear. Objectives: We hypothesized that CB leptin is positively associated with adiposity in peripubertal children and with childhood leptin. Methods: Leptin was measured in 986 cord blood and 931 childhood stored samples from a prospective birth cohort. Adiposity measures were collected at birth and mean age 11.5 years. Linear and logistic regression analyses were used to evaluate associations between log-transformed CB leptin and neonatal and childhood adiposity measures as continuous and categorical variables, respectively. Results: CB leptin was positively associated with neonatal and childhood adiposity. Childhood associations were attenuated when adjusted for maternal BMI and glucose, but remained statistically significant for childhood bodyfat percentage (?=1.15%, CI=0.46-1.84), bodyfat mass (?=0.69 kg, CI=0.16-1.23), sum of skinfolds (?=1.77mm, CI=0.31-3.24), log transformed child serum leptin (?=0.13, CI=0.06-0.20), overweight/obesity (OR=1.21, CI=1.03-1.42), obesity (OR=1.31, CI=1.04-1.66), and bodyfat percentage>85th percentile (OR=1.38, CI=1.12-1.73). Positive associations between newborn adiposity measures and cord blood leptin confirmed previous reports. Conclusion: CB leptin is positively associated with neonatal and childhood adiposity and child leptin levels, independent of maternal BMI and maternal hyperglycemia. CB leptin may be a biomarker of future adiposity risk.