Melatonin (MEL) is the main neurohormone of the pineal gland. Zinc (Zn) is an essential trace element that is required as a catalytic component for more than 200 enzymes. Both MEL and Zn are considered beneficial for anti-immunosenescence. Recent Findings have shown that MEL can modulate Zn turnover. The aim of this study was to investigate the effect of MEL treatment on the tissue Zn levels in young (4 months) and middle-aged (14 months) rats. Male wistar rats received during 3 weeks subcutaneous injection of MEL (10 mg/kg). After 3 weeks, rats were decapitated and tissue samples were collected. Zn levels were measured by spectrophotometric assay. In conclusion, MEL decreased liver Zn levels both in young and middle-aged rats. In addition, Zn levels in young control group were significantly higher than middle-aged control group. However, MEL treatment increased thymus Zn levels in middle-aged group compared with the control. These findings indicate that tissue Zn levels are significantly affected by MEL treatment.