Zinc modulates the human body defence against infections. Mild and medium deficiency in this mineral appears usually sub-clinically, being mistaken for other diseases, but the severe form can be fatal. The purpose of the study was to determine the plasma zinc concentration (PZC) for the most common infectious pathology in children. Zinc was measured in plasma using direct colorimetric assay based on the 5-Br-PAPS method (CV% 0.98-4.64%). In the paediatric patients, 0-3 years old, the PZC values were 15.20�1.37 μmol/L, with limits ranging between 13.05-20.6 μmol/L, the values falling within normal limits and proving the absence of zinc deficiency in the investigated population. During 3 years of follow up, 137 healthy children presented low values of plasma zinc concentration if they had acute lower respiratory infections, acute otitis media or giardiasis in past medical history. There were not found significant differences in case of children with viral or bacterial acute diarrheal diseases or viral exanthemas. In the present study, the children exposed to severe, complicated or chronic forms of infectious diseases were predisposed to low plasma zinc concentrations.