Laser ablation of poly(methyl methacrylate) and polystyrene films doped with porphyrins have been studied by etch depth measurement and time resolved spectroscopy. At the laser intensity above the ablation threshold, the broadening of fluorescence spectra of porphyrins was observed. The spectra broadened within laser pulse duration, which suggests that bulk polymer matrices were heated up by sensitizer molecules leading to the laser ablation. Transient changes in absorptivity of the films at the laser wavelength were found during the laser pulse. From these results, it is considered that repetitive photo‐absorption and relaxation in electronic excited states of sensitizers play a key role in sensitizer‐induced laser ablation. ©1996 American Institute of Physics.