A liposome preparation of a porphyrin photosensitizer for photodynamic therapy of tumors (PDT) was obtained. The in vitro efficiency of the photosensitizer was enhanced 2.5-fold through the liposome formulation. The composition and some properties of the new preparation were studied. An algorithm for a complex approach to the prediction of photosensitizer efficiencies by model experiments in vitro was developed. This approach is based on the use of two models: the determination of coefficient of distribution between n-octanol and a phosphate buffer, pH 7.4, and the determination of the cytotoxic effect on the culture of CaOv ovarian adenocarcinoma cells.