OBJECTIVE While the effects of age on the growth hormone/insulin‐like growth factor (IGF) axis are well documented, the influence of ethnic background is unknown. The differences in IGF and IGF binding proteins (IGFBPs) were investigated in two ethnic groups.DESIGN A cross‐sectional study of an age‐selected cohort of healthy, normoglycaemic, non‐obese Caucasian (C) and Asian (A) subjects.PATIENTS Fifty‐three (27 C, 26 A) subjects with a mean age (±SD) of 20.6±0.8 years were studied.MEASUREMENTS Fasting measurements of glucose, insulin, IGF‐I, IGF‐II, IGFBP‐1 and IGFBP‐3. Western ligand blotting and immunoblotting with IGFBP‐2 and IGFBP‐3 of serum samples.RESULTS There were no significant differences in IGF‐I levels between Caucasian and Asian subjects (C 218±55vsA 229±40μg/l;P=0.44). IGF‐II (C 707±110vsA 583±75μg/l;P<0.0001) and IGFBP‐3 (C 5.9±1.2vsA 5.12±1.17 mg/l;P=0.01) levels were significantly higher in Caucasian subjects. Immunoblotting of ligand blots revealed no protease activity on either IGFBP‐3 or IGFBP‐2 to account for these ethnic differences.CONCLUSIONS Ethnic differences in IGFBP‐3 and associated IGF‐II levels may affect the inter‐relationships of IGFs and their binding proteins and need to be c