Objective:To assess ovicidal activity of three acetonic extracts from the leaves of three forage legume,Calliandra calotyrsus(C.calotyrsus),Gliricidia sepium(G.sepium) and Leucaena diversifolia(L.diversifolia) in vitro on Haemonchus contortus(H.contortus).Methods:Eggs were exposed for 24 hours to five different concentrations(0.075,0.15,0.3,0.6 and 1.25 mg/mL) of acetonic extracts at room temperature(24℃).Distilled water and 0.4%Tween were used in the bioassay as negative controls.Results:The later did not affect embryonation and egg hatching of H.contortus.Conversively,significant effects were obtained with the acetonic extracts of leaves of all three plants and the maximum activity was observed with the highest concentration (1.25 mg/mL).The acetonic extract of G.sepium was found to be more active(2.9%and 0.0% for embryonation and egg hatching,respectively) than the other substances 16.5%and 33.5%, respectively for C.calothyrsus,33.7%and 33.3%,respectively for L diversifolia.Conclusions: These results suggest that the three forage legumes do possess ovicidal properties and further studies on larvae should be carried out. Objective: To assess ovicidal activity of three acetonic extracts from the leaves of three forage legume, Calliandra calotyrsus (C.calotyrsus), Gliricidia sepium (G.sepium) and Leucaena diversifolia (L.diversifolia) in vitro on Haemonchus contortus (H.contortus ). Methods: Eggs were exposed for 24 hours to five different concentrations (0.075,0.15,0.3,0.6 and 1.25 mg / mL) of acetonic extracts at room temperature (24 ° C). Distilled water and 0.4% Tween were used in the bioassay as negative controls. Results: The later did not affect embryonation and egg hatching of H. concourse. Conversively, significant effects were obtained with the acetonic extracts of leaves of all three plants and the maximum activity was observed with the highest concentration (1.25 mg / mL). The acetonic extract of G. sepium was found to be more active (2.9% and 0.0% for embryonation and egg hatching, respectively) than the other substances 16.5% and 33.5%, respectively for C. calothyrsus, 33.7% and 33.3 %, respectively for L diversifolia.Conclu sions: These results suggest that the three forage legumes do possess ovicidal properties and further studies on larvae should be carried out.