The modifications induced on PET, poly(ethylene terephthalate), by an excimer laser irradiation performed below the polymer ablation threshold were studied. The laser treatment of the polymer before aluminum thermal evaporation improved the Al-PET adhesion. The enhancement of the metal-polymer interface strength is attributed to surface morphological changes rather than to chemical modifications of the PET surface. Surface oxidation under UV irradiation was found to degrade the adhesion.