Objective: This in vitro study evaluated the whitening efficacy of LED and diode laser irradiation during the dental bleaching procedure, using the two agents Opalescence X-tra and HP Whiteness. Background: Bleaching techniques achieved significant advances with the use of coherent or incoherent radiation sources to activate the bleaching chemicals. Methods: Atotal of 60 bovine incisors were randomly divided into six groups, three for each bleaching agent, receiving 1) only agent, 2) agent and LED irradiation at wavelength of 470 nm, 3) agent and 1.6 watt diode Laser at 808 nm. The results of the irradiations were characterized with the CIELAB system by measuring the L*a*b* values for the teeth before and after bleaching. Results: The average increase of the lightness value (CIELAB L*) of the different groups was 3-7 and the average chroma value decreased by 5-9. Conclusions: This is to our knowledge the first time that the light sources Laser and LED are compared with respect to their whitening capability when applied to different agents. Best overall results are obtained with the Whiteness HP and Laser association.