Optical properties of metal-free 5,10,15,20-tetraphenylporphyrin (H2TPP) dispersed in a vacuum-deposited nylon-ii film were studied. When H2TPP was vacuum-deposited on the nylon-11 film, H2TPP showed a broad Soret band with peaks at 421 and 445 nm in visible spectrum. By the heat treatment at 120 degrees C, the Soret band showed significant broadening, and the purple color of the initial H2TPP/nylon-11 film turned to gray. As the amount of deposited H2TPP was increased, the intensity of the Soret band decreased. The time-resolved fluorescence spectroscopy for the H2TPP/nylon-11 film indicated that the fluorescence lifetime of H2TPP was much longer in the nylon-11 film than that in a vacuum-deposited H2TPP film on a glass plate. A possibility of formation of a complex between the dispersed H2TPP and the vacuum-deposited nylon-11 was suggested. After the heat treatment, the fluorescence lifetime of H2TPP was almost the same as that before the heat treatment, but the intensity of the fluorescence of H2TPP was decreased. Scanning electron microscopy indicated that rod-shaped crystallites with a size of ca. 5 mu m were observed in the heat-treated H2TPP/nylon-11 film. The remarkable broadening of the visible spectra of H2TPP/nylon-11 films, which was brought about by the heat treatment, was considered to be due to the crystal growth of the H2TPP-nylon complex.