Objective: To assess whether the K11391GOA polymorphism in the regulatory region of the adiponectin gene (ADIPOQ) is associated with birth size, postnatal growth, adiponectinemia, and cardiometabolic risk in adult life. Design: Case-control study nested within a prospective cohort of 2063 community subjects born in 1978/1979 and followed since birth to date. Methods: ADIPOQ K11391GOA genotype-phenotype associations were evaluated in 116 subjects born large for gestational age (LGA) and 392 gender-matched controls at birth (birth size), at 8-10 years (catch-down growth), and at 23-25 years of age (cardiometabolic profile). Results: The K11391A variant allele frequency was higher in LGA subjects (PZ0.04). AA genotype was associated with augmented probability of being born LGA (odds ratioZ4.14; 95% confidence interval: 1.16-16.7; PZ0.03). This polymorphism was associated neither with body composition nor with postnatal growth pattern. At the age of 23-25 years, the K11391A variant allele was associated with higher serum adiponectin levels (GG: 10.7G6.2 versus GA: 12.2G6.5 versus AA: 14.2 G6.8 mg/ml; P!0.01). Subjects born LGA presented higher body mass index (BMI; PZ0.01), abdominal circumference (PZ0.04), blood pressure (PZ0.04), and homeostasis assessment model for insulin resistance (PZ0.01) than adequate for gestational age. Symmetry at birth did not influence these variables. The occurrence of catch-down of weight was associated with lower BMI and abdominal circumference (P!0.001) at 23-25 years. Conclusions: The K11391A ADIPOQ gene variant was associated with increased chance of being born LGA and with higher adiponectin levels in early adult life.