Lead pollution is a substantial problem in developing countries such as India. The US Centers for Disease Control and Prevention has defined an elevated blood lead level in children as > or = 10 microg/dl, on the basis of neurologic toxicity. The US Environmental Protection Agency suggests a threshold lead level of 20-40 microg/dl for risk of childhood anemia, but there is little information relating lead levels <40 microg/dl to anemia. Therefore, the authors examined the association between lead levels as low as 10 mug/dl and anemia in Indian children under 3 years of age. Anemia was divided into categories of mild (hemoglobin level 10-10.9 g/dl), moderate (hemoglobin level 8-9.9 g/dl), and severe (hemoglobin level <8 g/dl). Lead levels <10 mug/dl were detected in 568 children (53%), whereas 413 (38%) had lead levels > or = 10-19.9 microg/dl and 97 (9%) had levels > or = 20 microg/dl. After adjustment for child's age, duration of breastfeeding, standard of living, parent's education, father's occupation, maternal anemia, and number of children in the immediate family, children with lead levels > or = 10 microg/dl were 1.3 (95% confidence interval: 1.0, 1.7) times as likely to have moderate anemia as children with lead levels <10 microg/dl. Similarly, the odds ratio for severe anemia was 1.7 (95% confidence interval: 1.1, 2.6). Health agencies in India should note the association of elevated blood lead levels with anemia and make further efforts to curb lead pollution and childhood anemia.