Traditionally animals and cell cultures have been used to assess the toxic potential of xenobiotics on cell membranes. In search for more reproducible, quantitative, cost- and time-effective assays, toxicologists have recently become interested in biomimetic lipid vesicle-based test systems. Lipid vesicles (liposomes) have long been appreciated as simple cell membrane models in biochemical and biophysical studies providing a good understanding of the physicochemical properties of liposome systems. More recently a number of reports have been published on the interactions of toxic substances with vesicles. Literature reports on liposome assays have appeared for widely different classes of xenobiotics, such as dental materials, antibiotics, detergents, and peptides. In this review we focus on those reports that contain a quantitative and significant correlation with more established toxicological tests like cell culture assays. We provide an introduction to the structure and main characteristics of vesicles and related lipid aggregates. The two main assays presented are leakage of fluorescence dyes and differential scanning calorimetry (DSC) measurements of the solid-ordered/liquid-disordered main phase transition temperature (Tm).