The National University of Singapore Heart Study is a cross-sectional survey of cardiovascular risk factors in persons aged 30 to 69 years from the general population of Singapore, with 957 persons having measurements of serum ferritin. For males aged 30 to 69 years, mean serum ferritin concentrations were highest in Chinese (236 micrograms/L), followed by Malays (175 micrograms/L) and then Indians (132 micrograms/L). For females aged 30 to 49 years (pre-menopausal), mean levels were higher in Chinese (61 micrograms/L) and Malays (55 micrograms/L) than Indians (30 micrograms/L), and likewise for the 50 to 69 years age group (post-menopausal) where the mean values were 144 micrograms/L for Chinese, 141 micrograms/L for Malays, and 85 micrograms/L for Indians. The proportions with iron deficiency (serum ferritin < 12 micrograms/L) were low in males aged 30 to 69 years (1.9%) and in females aged 50 to 69 years (2.6%), but fairly high in females aged 30 to 49 years and was highest in Indians (23.0%), followed by Malays (15.6%), and then Chinese (7.8%). The much lower ferritin in Indians is maybe partly due to their more vegetarian diet and binding of dietary iron by phytates, but other mechanisms probably exist. Only 0.4% of males and no females had serum ferritin > or = 1000 micrograms/L. Levels of serum ferritin were somewhat higher than that reported in the USA. The overall iron status in Singapore seems to be satisfactory, although pre-menopausal females (especially Indians) have a fairly high rate of iron deficiency and these females need to be identified and treated with iron supplementation.