The importance of Zinc (Zn) as a necessary oligoclement for human nutrition begins in the first three decades of life. At the moment, the role that Zn plays in the infantile nutrition is very well-known, acquiring a special connotation in children with proteic-energetics malnutrition (PEM). In this study the daily ingestion and the serum measuremets of Zn were determined in 64 undernourished children (light, mild and severe) and in 25 eutrophic children with ages between 1 to 5 years, belonging to families of the strata IV and V according to the Graffar scale corrected by age. The results of the serum values of Zn were for the light undernourished of 39.73 +/- 14.97 microg/dL (30.38 microg/dL-44.56 microg/dL), for the mild undernourished of 35.07 +/- 28.13 microg/dL (27.76 microg/dL-65.80 microg/dL) and for the severe undernourished of 15.48 +/- 10.44 microg/dL (5.57 microg/dL-28.56 microg/dL), which were diminished in relation with the control group, 76.71 +/- 33.29 microg/dL (45.75 microg/dL - 78.27 microg/dL) with p < 0.0001. Equally, there were significant differences (p < 0.001) among the group of severe undernourished with the light undernourished and normal subjects. In relation with the daily ingestion of Zn, a statistically significant difference was observed only (p < 0.001) in the severe undernourished, 1.87 +/- 0.54 mg/día (1.20 mg/día-2.87 mg/día) when comparing them with the light undernourished, 5.48 +/- 0.98 mg/día (3.50 mg/día-7.87 mg/día), the mild undernourished, 4.99 +/- 1.24 mg/día (4.10 mg/día-11.42 mg/día) ) and the normal subjects, 6.22 +/- 0.98 mg/día (4.8 mg/día-8.02 mg/día). There was a positive correlation between ingestion and seric values of Zn when the 3 undernourished groups were studied. These results allow to conclude that both the seric values of Zn and its ingestion show modifications in relation with the degree of nutritional deficiency.