This in vitro study aimed to evaluate the effectiveness of Caffeic acid against the viability of Leishmania tropica promastigotes in vitro. The result showed that Caffeic acid had a fatal effect on the viability of Leishmania tropica promastigotes with the use of different concentrations leading to a gradual decreasing of living promastigotes number with the increase of Caffeic acid concentration. The mean parasiticidal effect of Caffeic acid was (24×104, 30×104, 38×104, 44×104, 53×104) promastigote /ml at concentrations (10, 15, 20, 25, 30) mg/ml respectively after three days of incubation. It can be concluded that Caffeic acid posses a cidal effect on the Leishmania tropica promastigotes in vitro." P < 0.01 ".