Laboratory bioassay of methanol extracts of Murraya koenigii, Citrus paradisi and their combinations were evaluated against the third infectious stage of Similium yahense .The in vitro test with concentrations ranging from 0.5%-5.0% revealed that the extract of the plants and their combination posses lavacidal activities as they could induce significant mortalities of the microfilaria on a dose dependent response. The LC50 values estimated for M.koenigii C. paradisi and their combinations are 1.96, 1.85 and 1.67 respectively. The extract obtained from their combination was found to be more effective while the extract obtained from M.koenigii was shown to be the least effective.
