An assay method for the excipients (sucrose, phosphatidylcholine, and cholesterol) of liposomal medicinal formulations of the phthalocyanine photosensitizer lipophthalocyan by TLC with chromatodensitometry was validated. Coefficients of standard residual deviation for establishment of linearity were 3.48 for sucrose, 1.69 for phosphatidylcholine, and 1.36 for cholesterol. The coefficients of variation for determination of similarity and intermediate precision were less than 5%. The method was shown to be reliable over a wide range of conditions for the suitability of the system.