Laser spark plug for an internal combustion engine has at least one laser unit for guiding, shaping and/or generating laser radiation, further including a combustion chamber window, and a housing which has, on the opposite side of the combustion chamber window from the laser unit, an aperture for the passage of the laser radiation guided, shaped and/or generated by the laser unit into a combustion chamber, the length of the aperture being 4 mm or more.