The pregnant teenager is considered at nutritional risk specially due to the fact that most of them still growing and developing. Therefore the demands of pregnancy compete with those of growth causing an extra need for her and the fetus (1). Iron, zinc and folate are essential nutrients that are frequently low on the teenagers diet. Besides that there is not much specific information available about these nutrient recommendations and their interaction among each other. The data available is limited and demands more investigation. This study was conducted at a Public Maternity Hospital located at Teresina, Piauf, Brazil. The main objective of this study was to investigate the effect of different concentrations of iron supplementation (80 and 120 mg of ferrous sulfate) together with folate (250 micrograms) and zinc (5 mg) on the hemoglobin concentration and iron stores (plasma ferritin) of pregnant adolescents. The supplementation was done from the 16th to 20th weeks of gestation until delivery. The data founded proved that either 80 mg or 120 mg of iron supplements had similar effect on the improvement of hemoglobin concentration although results showed no statistical significance.