Mild postnatal anemia is common. However, determination of postnatal hemoglobin level or iron supplementation are not routine in many obstetric units. This study was designed to evaluate the impact of mild postnatal anemia and iron supplementation on women. One hundred fifty women who had postnatal hemoglobin levels between 80 and 99 g/L were randomly assigned into two groups with iron tablets or placebo provided from the time of diagnosis until reassessment at 6 weeks. The patients' general well-being, hemoglobin levels, iron status, side effects, and compliance were assessed. One hundred twenty-two women returned for reassessment. Twelve (9.8%) of the 122 women recruited and four (3.2%) of 122 nonanemic matched controls complained of dizziness 2 days after delivery; the difference was statistically significant (chi2 test, p<0.05). At 6 weeks postpartum, significantly more women were anemic (chi2 test, p<0.05) and iron deficient (chi2 test, p<0.01) in the placebo group. The score of general well-being as assessed by a 4-point scale was significantly higher in the iron supplementation group (Mann-Whitney test, p<0.05). The amounts of drugs consumed in both groups were comparable and the incidences of side effects were similar.