The effect of oral iron supplementation was assessed on blood iron levels and Pb and Cd levels in erythrocytes, hair and urine of 101 Puchon 5th grade school children with suboptimal iron status. Treatment with 25mg of elemental iron per day for 8weeks resulted in a significant increase in the intake of most nutrients in addition to iron. Iron supplementation resulted in significant improvements in hemoglobin, MU, MCH, MCHC, serum ferritin, serum iron, TIBC, and transferrin saturation of subjects(p<0.05 - p<0.01) and cocomitantly lowered Pb and Cd levels in erythrocytes, hair, and urine(p<0.01). Regression analysis showed that only iron intake contributed to significant increases in hemoglobin and serum ferritin. It seems that 25mg of iron supplementation is safe and adequate to improve iron status in school children with suboptimal iron status and it also has the benefit of alleviating Pb and Cd status. (Korean J Nutrition 31(7) : 1165-1173, 1998)