A family of benzoporphyrins formed by differently substituted metallo tetrabenzoporphyrins and one opp-dibenzoporphyrin has been prepared. The former benzoporphyrins, and meso- tetra(m-hydroxy-phenyl)chlorin (m-THPC) to act as reference, have been encapsulated into liposomes and subjected to preliminary in vitro and in vivo assays to test their efficacy as photosensitizers in the photodynamic therapy of cancer. The results of the photocytotoxicity test shows that, with the exception of the nickel complexes 5, and 7/8, the other porphyrins are photobiologically active, the Mg-tetrabenzoporphyrin 1 and the opp-dibenzoporphyrin 10 being the most active. The dark toxicity of the photoactive porphyrins is in the range described for many photosensitizers, including HPD. The in vivo assays show no toxicity in the liver for any of the compounds tested, and also that 2 is the most promising photosensitizer among them, because of an efficient localization in an experimental mouse tumor.