Treatment of cutaneous leishmaniasis by antimonial compounds when administered by various routes to mice infected with Leishmania major or L. mexicana amazonensis is enhanced, relative to the free drug, by entrapment of these compounds within liposomes. The efficacy of the liposome treatment is dependent on the time and route of administration, and upon the phospholipid composition of the liposomes themselves. Drug-loaded liposomes administered intravenously (i.v.) are more effective at reducing the growth of a cutaneous lesion if they are administered after the nodule has begun to develop, rather than at the time of inoculation of the parasites. In contrast to the i.v. route, liposomes administered subcutaneously (s.c.) at the inoculation site are only effective if given at the time of infection.