Objective 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 1 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.