Dynamic studies of the hydration and removal of phospholipid films attached to solid substrates were performed. The phospholipids used were 1,2-dipalmitoyl-sn-glycero-3-phosphatidylethanolamine (DPPE), and a modification of DPPE containing a fluorescent molecular probe: n-(5-fluoresceinthicarbamoyl)-1,2-dipalmitoyl-sn-glycero-3-phosphatidylethan olamine, triethylammonium salt (FITC-DPPE). The phospholipid films were exposed to water and aqueous solutions of the anionic surfactant sodium dodecyl sulfate (SDS). The film mass was determined as a function of time by means of a quartz crystal microbalance (QCM). The crystalline structure of the film during the hydration process was analyzed by means of wide-angle X-ray diffraction. At low surfactant concentrations (below 20% of the critical micelle concentration (CMC)), the presence of surfactant increased the hydration rate of the film, as well as its maximum water uptake. At surfactant concentrations as low as 50% of the CMC, competitive hydration and removal of the phospholipid film were observed. X-Ray diffraction measurements show that the crystal structure of the DPPE films did not change significantly upon exposure to water and surfactant solutions. In contrast, FITC-DPPE films exhibited changes in the long-range spacing of their crystalline structure upon hydration.