Passive permeability is a critical molecular property studied in drug discovery because of its strong influence on pharmacokinetics. It plays an essential role in the gastrointestinal absorption of oral drugs, penetration of the blood-brain barrier (BBB), and renal reabsorption. The permeability coefficient (cm•s -1 ) is the quantitative measure of permeability, often presented as a decimal logarithm (logPerm). Numerous methods for their determination have been developed because of the importance of permeability coefficients in pharmaceutical research. We can, in general, divide the approaches into cell-based in vivo experimental assays, membrane-based in vitro experimental essays and in silico approaches.