Medicinal plants and their derivations are used as safe agents for the treatment of parasitic diseases. This preliminary study investigates antileishmanial activities of Peganum harmala essential oil (PHEO), Achillea millefolium essential oils (AMEO) and their combinations against Leishmania infantum promastigotes. A standard strain of L. infantum promastigote was cultured in a 96-well Novy-MacNeal-Nicolle media culture and antileishmanial activities of glucantime, PHEO, AMEO, an equal ratio of both and 80% PHEO+20%AMEO were investigated in concentrations of 10, 100, 500 and 1000 mg/mL and interval times of 24h, 48h and 72h. The results showed that greatest inhibition was observed in 50PHEO+ AMEO and lowest inhibition was seen in control group. The increased time and increased concentration significantly increased their efficiencies. The analyses showed a significant interaction between time and agents [F (10, 360)=7.84, P=0.000]. The agents showed better effects with increased time. In sum, an equal combination of PHEO and AMEO showed its potential as an antileishmanial safe structure and must be considered for future studies.