The role of metallothioneins (MTs) in aging is not completely understood. Several studies have shown evidence that these proteins could represent a defense system against oxidative damage, but survival studies on mice overexpressing MTs are poor. Here we describe a survival study performed on old MT-1-overexpressing mice (MT-TG) and their respective controls (C57BL/6J) fed a standard or zinc (Zn)-supplemented diet. MT-TG mice had significantly increased survival compared with control. Zn supplementation affects the survival curves of MT-TG and C57BL/6J mice differently. This study poses the basis for intervention based on gene therapy with MTs to enhance the health span of laboratory mice.