Hepatic cells are involved in the metabolization and elimination of a variety of endogenous and exogenous substances. They mediate the uptake, processing and subsequent secretion of biliary compounds, such as various drugs or hormones, and the passage of metabolites to be released into different blood compartments. To perform vectorial passages hepatocytes show a strong polarity with sites for endocytotic processes or specific carrier molecules, and a specified system of organelles for intracellular transport and sorting, metabolization and secretion of compounds. Several aspects, e.g. regulation, control and mechanisms of hepatic traffic are reported in detail – complemented by methodological approaches to analyse and monitor these processes.