Abstract: HPLC and TLC analyses of an antitumor photosensitive drughematoporphyrin derivative (HPD) prepared by using protoporphyrin as its starting material revealed that it was a complex mixture of porphyrins. Separation of its methyl ester derivatives afforded eleven compounds. Seven of them were characterized as protoporphyrin dimethyl ester, a pair of 3-(1-hydroxyethyl)-8-vinyldeuteroporphyrin dimethyl ester (HVD)isomers, a pair of 8-(1-hydroxyethyl)-3-vinyldeuteroporphyrin dimethyl ester isomers, 8(3)-(1-hydroxyethyl)-3(8)-ethoxyethylporphyrin dimethyl ester and hematoporphyrin dimethyl ester. The result was very similar to that reported by other investigators. In addition, we were able to obtain four isomers of HVD as the main constituents of HPD.