The biological potential of a synthetic copper chlorophyll derivative was investigated via in vivo and in vitro experiments. The Cu-chlorophyll derivative photosensitizer (Cu-PH-A) was labeled with I-131 with high efficiency (92.9 +/- 4.2%) using the iodogen method. Cell culture studies were performed with the MCF-7 and MDAH-2774 cell lines after radiolabeling. The photosensitizing activity of Cu-PH-A was more effective in MDAH-2774 cells than in MCF-7 cells at a concentration of 50 mu M. When the biodistribution in female Albino Wistar rats was examined, uptake of the radiolabeled photosensitizer was maximal in the liver and ovaries after 60 min. It is concluded that radiolabeled Cu-chlorophyll derivative photosensitizer has high uptake in ovaries in normal rats. In addition, the intercellular uptake and PDT efficacy of the Cu-PH-A in MDAH-2774 were good compared with MCF-7 cells. This photosensitizer could be useful for both ovary tumour imaging and PDT.