A method for the preparation of pheophorbide a(a novel photosensiti-zer for tumor photolocalization and photodynamic therapy)from silkwormexcrement oily chlorophyll is reported.The chromatographic,spectroscopic andphotochemical properties of pheophorbide a were studied,and its distribution intissues of S180 tumor-bearing mice was determined.The UV/visspectrum of the obtained pheophorbide a was identical with thatreported by other authers,but it was still found to contain at least twocomponents(probably two optical isomers)by HPLC analysis and~1H-NMR spectrometry.The results of a preliminary study on itsdistribution in tumor-bearing mice showed that it was accumulatedselectively in tumor tissues after intravenous injection and at 24 hoursafter drug administration the tumor to skin ratio rose to as high as 15. A method for the preparation of pheophorbide a (a novel photosensiti-zer for tumor photolocalization and photodynamic therapy) from silkwormexcrement oily chlorophyll is reported. Chromatographic, spectroscopic and photochemical properties of pheophorbide a were studied, and its distribution intissues of S180 tumor-bearing mice was determined. The UV / visspectrum of the obtained pheophorbide a was identical with thatreported by other authers, but it was still found to contain at least twocomponents (probably two optical isomers) by HPLC analysis and ~ 1H-NMR spectrometry. the results of a preliminary study on itsdistribution in tumor-bearing mice showed that it was accumulatedselectively in tumor tissues after intravenous injection and at 24 hoursafter drug administration the tumor to skin ratio rose to as high as 15.