Zinc is an important micronutrient for humans. Trials with zinc have shown positive effects of supplementation on growth, but there is still a lack of results on schoolchildren population. This Randomized Double-Blind Controlled Trial was design to measure the effect of weekly zinc supplementation on schoolchildren with growth deficit and normal stature. Schoolchildren were allocated into two homogeneous groups named Growth Deficit (HAZ < -1,5 Z-score), and Normal Stature (HAZ between -1,0 and ±1,0 Z-score) and were randomly assigned to compose two exposed and two control groups to receive a supplement of 30mg of zinc amino acid chelate or placebo individually once a week, during 12 weeks. Children's heights were measured at the end of supplementation period and again after 12 weeks.