The synthesis, characterization, and biolocalization properties of new, fully water-soluble sapphyrins is reported. These systems, which display light absorbing features that make them of potential interest as photodynamic therapy (PDT) sensitizers, were found to localize selectively in pancreatic carcinoma tissue in a xenographic murine model. In this model, the concentration ratios for malignant tissue to surrounding muscle tissue were found to be as high as 280 in the most favorable case. The concentrations of the water-soluble sapphyrins reported here, as well as a porphyrin control system, were determined as a function of time and tissue type.