The possibility to use the liposomes as drug vehicles has been largely investigated in recent years. Most of the studies have been carried out in animals and are related to disease involving predominantly the reticulohistiocytic system. Attempts to use these liposomes orally (induced diabetes) or locally (induced arthritis) are also reported. Further trials are required to get a better knowledge of the mechanisms involved in the exchanges between the cell membrane and the liposome the latter being variable as regards its composition, size and permeability according to the various investigators; the adjustment to the liposome of a complex capable to electively direct it towards the target organ is studied.