The absorption spectra of iodine as well as the fluorescence spectra of phenosafranin in sonicated dispersion of phosphatidylcholine (PC) of various concentrations in water show a remarkable change when PC concentration is above 1.60 í— 10-5 mol dm-3. The absorption spectra of iodine in other phospholipids such as lyso-PC, sphingomyelin (SM), phosphatidylethanolamine (PE) and lyso-PE show the similar results.