Probing Fluoroquinolones-lipid interactions at the molecular level represents an important challenge in both membrane biophysics and pharmaceutical research. As the pharmacological target of these drugs is intracellular, they must pass across the bacterial membranes. Likewise, Fluoroquinolones enter eukaryotic cells, which imply their ability of interacting with lipids membranes. This book, therefore, characterize the effect of two closely related drugs ciprofloxacin CIP and moxifloxacin MXF on physicochemical properties of the major phospholipids that are mimicking the prokaryotic and the eukaryotic lipid membranes, respectively. Several models of lipid membranes and biophysical methods (Atomic force microscopy, Langmuir-Blodgett technique, as well as fluorescence, infra-red, nuclear magnetic resonance spectroscopies) are described. Our data suggest that the first step in the interaction of CIP with lipid membranes relates to its binding to the headgroups of phospholipids and that MXF is located in a more hydrophobic environment of the membranes. Our work may help in shedding more light on the role played by lipids in the drugs transport, and should be useful to young researchers.