In order to evaluate the effects of iron therapy on weight and height, we studied 65 children with a mean age of 32 months who were assigned to oral iron therapy with 4-5 mg/kg/day of elemental iron as ferrous sulfate or ferric hydroxide polymaltose for 8 weeks. The medicine was distributed to the patients and its consumption was checked fortnightly. Statistically significant increases in hemoglobin, serum iron and transferrin levels and in transferrin saturation and ferritin levels were observed. The weight-for-age and weight-for-height Z-scores were determined using the ANTHRO computer software (CDC/WHO) which, based on birth and examination dates, permits age estimates with centesimal accuracy for the months using the National Center for Health Statistics (NCHS) standards. Mean Z-scores before and after iron therapy demonstrated a significant increase in weight-for-age (Z = -0.53 after, P < 0.01) and weight-for-height (Z = 0.19 before and -0.08 after, P < 0.01) indices, but not in the height-for-age index (Z = -0.46 before and Z = -0.46 after iron therapy). A significant decrease in the number of children with inadequate weight-for-age (< 90%)) and weight-for-height (< 90%) indices was observed after iron therapy in patients aged less than 60 months. In conclusion, oral iron therapy for a period of 8 weeks led to a significant weight gain.