A new liquid culture medium prepared with chemicals that can be obtained economically and commercially was tested in in vitro cultivation of Leishmania promastigotes to obtain a large number of organisms to use in serological studies. The number of Leishmania infantum and Leishmania tropica promastigotes taken from Novy-MacNeal-Nicolle (NNN) medium reached 1 x 10(7)/ml at the end of the 8th day in our new medium, though in NNN medium the number of organisms reached only 5 x 10(6)/ml. After 10 subsequent passages, the culture medium prepared was evaluated as being quite inexpensive, simple, and successful compared with other commercially available liquid culture media.