['Iron supplements improve hemoglobin status and reduce anemia due to iron deficiency. It is not known whether multiple micronutrient (MM) supplements are as efficacious as are iron supplements alone in improving hemoglobin concentrations.', 'We conducted a randomized, double-blind community trial in Mexico to compare the efficacy of MM supplements containing iron with that of iron alone in improving hemoglobin concentrations in nonpregnant women.', 'Nonpregnant women (n = 158) were recruited from a semirural community in Mexico and were randomly assigned to receive iron alone (60 mg; Fe group) or MM supplements (vitamins A, B complex, C, D, E, and K and iron, zinc, and magnesium; MM group) 6 d/wk in their home for 12 wk. Hemoglobin concentrations were measured in capillary blood samples at baseline and follow-up.', 'The treatment groups (MM: n = 75; Fe: n = 77) did not differ significantly at recruitment in age, schooling, literacy, or socioeconomic status. There were no significant differences between groups in compliance (median: 97.5%), baseline hemoglobin concentrations, or prevalence of anemia (20%). Losses to follow-up (4%) and mean (+/-SD) changes in hemoglobin (MM group: 6.7 +/- 10.6 g/L; Fe group: 7.1 +/- 13.6 g/L) were not significantly different between groups. However, the change in hemoglobin in anemic subjects was greater in the Fe group than in the MM group (P < 0.05 for interaction), and there was no significant difference in nonanemic subjects.'] Is multivitamin-mineral supplementation as efficacious as is iron supplementation in improving hemoglobin concentrations in nonpregnant anemic women living in Mexico?