The photodegradation of photochromic compounds in spiro[fluorene-[2H]-chromene] series in toluene has been studied by continuous irradiation. We have shown that the resistance to the photodegradation is a function of the introduced heterocycle, As in spiro[indoline-naphthoxazine] series, the chromenes heteroannelled by a benzofurane or a pentamethylene pattern present a dramatic decrease of their resistance to the photodegradation, Then, comparatively to the diaryl-[2H]-chromenes, the increasing flatness of the open forms issued from the spiro[fluorene-[2H]chromenes] leads to a lower stability in connection with a bathochromic shift and the apparition of an additional band in the visible spectrum.