To assess the effectiveness of complementary food supplements with protein and multi-micronutrients on hemoglobin and anemia in infants and young children.Methods In 5 poor counties of Gansu,984 children aged 6-12 months were enrolled and divided into two groups.In addition to the usual home-made complementary food,all the children were fed one sachet of either Formula I or Formula II supplements each day.Protein and micronutrients were provided in Formula I,while the same energy intake was secured in Formula II as in Formula I.A massive dose of vitamin A was supplemented to all the children every 6 months.Hemoglobin test was done at the same time.Results Prevalence of anemia was about 35% in both Formula I and Formula II group at baseline,and there were no differences in hemoglobin concentration between the two groups.During the 6-month and 12-month supplementation,hemoglobin of children in Formula I group was higher than that in Formula II group(P<0.05),and hemoglobin increase in Formula I group was significantly higher than that in Formula II group(P<0.001).After 6-and 12-month supplementation,the prevalence of anemia in Formula I group dropped to 19.1% and 8.2% respectively,and it was 28.0% and 12.4% in Formula 2 group.The prevalence of anemia in Formula I group was significantly lower than that in Formula II group(P<0.05).After adjusting age and hemoglobin level at baseline,the hemoglobin increase at age of 24 months in formula 1 group was higher(10.7 g/L vs 7.9 g/L,P<0.0001).Conclusion Micronutrient fortified complementary food supplements,with large-dose vitamin A,is effective for children aged 6-12 months in terms of iron deficiency prevention. To assess the effectiveness of complementary food supplements with protein and multi-micronutrients on hemoglobin and anemia in infants and young children. Methods In 5 poor counties of Gansu, 984 children aged 6-12 months were enrolled and divided into two groups. Addition to the usual home-made complementary food, all the children were fed one sachet of either Formula I or Formula II supplements each day. Protein and micronutrients were provided in Formula I, while the same energy intake was secured in Formula II as in Formula IA massive dose of vitamin A was supplemented to all the children for 6 months. Hemoglobin test was done at the same time. Results Prevalence of anemia was about 35% in both Formula I and Formula II group at baseline, and there were no differences in hemoglobin concentration between the two groups. During the 6-month and 12-month supplementation, hemoglobin of children in Formula I group was higher than that in Formula II group (P <0.05), and hemoglobin increase in For mula I group was significantly higher than that in Formula II group (P <0.001). After 6-and 12-month supplementation, the prevalence of anemia in Formula I group dropped to 19.1% and 8.2% respectively, and it was 28.0% and 12.4% in Formula 2 group. The prevalence of anemia in Formula I group was significantly lower than that in Formula II group (P <0.05). After adjusting age and hemoglobin level at baseline, the hemoglobin increase at age of 24 months in formula 1 group was higher (10.7 g / L vs 7.9 g / L, P <0.0001) .Conclusion Micronutrient fortified complementary food supplements, with large-dose vitamin A, is effective for children aged 6-12 months in terms of iron deficiency prevention.