Although known primarily for its antioxidant function, zinc appears to be an important modulator for the production of immune cells as well as ensuring the proper action of various leukocytes such as neutrophils, monocytes, macrophages, B and T lymphocytes. The primary study objective was to compare URI incidence between supplemented (zinc gluconate 15mg/day capsules) and non-supplemented (corn-starch placebo) groups. This study was a seven month randomized, double blind, placebo-controlled trial involving 40 cadets to evaluate zinc's effectiveness in reducing the risk of upper respiratory infections (URIs). Self-reported symptoms as recorded by a weekly web site survey revealed that supplemented participants experienced significantly more symptom free episodes than those in the placebo group (p=0.01). No significant differences were found between groups in terms of physician diagnosed cases (p=0.99). Higher zinc dosage may be warranted to confer a protective effect under more challenging immunological conditions.