A selective and sensitive micelle-stabilized room-temperature phosphorimetric (MS-RTP) method for the determination of naphazoline in pharmaceutical preparations is described. The method is based on obtaining a phosphorescence signal from naphazoline using a micellar agent (sodium dodecyl sulfate), a heavy atom salt (TINO3) and a deoxygenation agent (Na2SO3). Optimization of the various conditions permitted the establishment of an MS-RTP method for naphazoline determination with a detection limit of 64.2 ng ml-1 and a relative standard deviation of 3.74% at the 500 ng ml-1 level. The method was applied to the analysis of pharmaceutical preparations.