Phospholipids represent the major element of the bilayer matrix of our cell membranes. Their organization and dynamics are critical to the functions of membranes and they have been studied by various physical techniques, including infrared and Raman spectroscopies. In fact, vibrational spectroscopy is extremely informative about the packing of the lipid hydrocarbon chains and it allows to probe different parts of the molecule simultaneously. Pressure perturbations have been used to explore the polymorphism of phospholipids. The correlation field splitting and pressure dependence of the acyl chain packing and of the molecular interactions. The effect of chain monounsaturation has been investigated. Increases in hydrostatic pressure can also trigger changes in the conformation of the head group and of the backbone of the molecule.