Neutron reflectometry is widely used nowadays in cell membrane research. However, most researchers using this technique investigate model membranes, composed by one to three different synthetic lipids and assuming often that they behave as natural ones. We have started investigating the structure of natural yeast membranes and plan to study their interaction with the antifungal drug amphotericin B (AmB). During experiment 8-02-593, we investigated the structure of total hydrogenated and deuterated yeast lipids and their interaction with AmB by neutron reflectometry. In this proposal, we plan to study the structure and the interaction of polar yeast lipids with AmB. Tests by TLC were done to be sure to separate phospholipids from the apolar lipids. We did some QCM-D characterization to be sure that the polar lipid can form a bilayer on the substrate. Including the time for characterizing the bare substrates plus the calibration measurements and characterization of all bilayers in four contrasts, we estimate that 4 days of beamtime will be needed on D17 or FIGARO.