Context: Adiponectin, high-density lipoprotein cholesterol (HDL-C)and insulin concentrations may be important in the pathophysiology of cardiovascular disease. Objective: We tested the hypothesis that serum adiponectin rather than insulin differs from early life, between South Asians and Europeans, with a potentially key role in excess cardiovascular risk characteristic of adult South Asians. Design and Participants: We conducted a longitudinal study of 215 British-born children of European (n = 138) and South Asian (n = 77) origin, from birth to 3 yr. Main Outcome Measure: Serum adiponectin, insulin, proinsulin and HDL-C concentrations were assessed in relation to ethnic group and growth in anthropometric variables from 0-3 yr of age. Results: Serum adiponectin was lower in South Asian children, despite their smaller size, notable at age 3-6 months (9.5 vs. 11.8 mg/liter; P = 0.04), with no ethnic differences in serum lipids or insulin or proinsulin. In mixed-effects longitudinal models for HDL-C, determinants were adiponectin (P = 0.034), age (P <0.001), and body mass index (P <0.001) but not ethnicity. None of theseor growth variables affected either insulin or proinsulin. In a fully adjusted mixed-effects longitudinal model including age, sex, insulin, and proinsulin, the independent determinants of serum adiponectin were height [21.3 (95% confidence interval = 31.7-10.8 cm lower, for every 1 mmol/liter increase in adiponectin, P <0.001], HDL-C [2.8 (1.3-4.2) mmol/liter higher, P <0.0001], bodymass index (lower, P = 0.03), and South Asian ethnicity (lower, P = 0.01). Conclusions: These British South Asian-origin infants have lower serum adiponectin but no differences in HDL-C or insulin molecules. In South Asians, factors affecting adiponectin metabolism in early life, rather than insulin resistance, likely determine later excess cardiovascular risk. Copyright © 2011 by The Endocrine Society.