The zinc levels of plasma, erythrocytes, hair and urine were determined by atomic absorption spectrophotometer technique in 20 homozygous β-thalassemic and 20 control children. Plasma, erythrocyte and hair zinc levels in the diseased children were found to be much lower than those of controls. The difference was statistically highly significant. Along with other factors, zinc deficiency was wrought to have an important role in the retardation of growth and sexual development seen in the patients with homozygous β-thalassemia. The increased urinary zinc excretion suggests that the factor responsible for zinc deficiency might be the loss of the element through the kidneys.