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