Lyotropic phases of hydrated 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) are generally considered as models of biological membranes. Effects of lauric acid (LA) and fenspiride (FS) on DPPC membrane were studied by differential scanning calorimetry and fluorescence spectroscopy with environment-sensitive probe PH7 (2-(2'-hydroxy-phenyl)-phenanthro[9,10-d]-1,3-oxazole). FS decreases pretransition- and gel-to-liquid crystal phase transitions temperatures of DPPC membrane and extends temperature range of ripple phase, contrary to LA. Meanwhile, LA and FS cause membrane fluidization in the gel and liquid crystalline phases, with perturbation effects more pronounced for LA.