The absorption, fluorescence spectra and fluorescence life time of hematoporphyrin oligomers (Hpos: mean molecular weight=2000, 3000, 5000 and 12000) and gerumanium hematoporphyrin derivatives (Ge HpD) were compared with those of photofrin II which has been using in photodynamic therapy (PDT). The proportion of the major lifetime component (14.5ns) of photofrin II was 90.5%.The fluorescence lifetime of Hpo (3000) was 13.3ns. The proportion of the major lifetime component of Hpo (3000) was 89.8%. From these results obtained, it was suggested that the probability of the photosensitizing react ion of Hpo 3000 might be high.
