Lemon grass (Cymbopogon citratus Stapf)is a popular altative to west medicines for a number of condi-tions,including fevers,muscle soreness and superficial infections in Nigeria.In addition to its already reported suppressive effects against P.berghei infection,this study sought to determine its repository and blood schizon-ticidal activities in established P.berghei infection using Swiss albino mice as models.Mice weighing on aver-age,between 15 and 25g were given 103mg/kg,155mg/kg and 310mg/kg/day of the crude aqueous extract of cymbopogon citratus stapf,in the 4-day test,24-hour Rane test and 72-hour Rane test.The effects of these do-ses of the extract were then compared with chloroquine (5mg/kg/day)and sulphadoxine /pyrimethamine (3mg/kg/day).We report an average percentage suppressive repository activity of 65.8% for the extract at a dose of 310mg/kg and a blood schizonticidal activity that increased from 68.33% in the 24-hour Rane test to 92% in the 72-hour Rane test for the same dose of extract.The crude aqueous extract of C.citratus stapf thus has significant repository and blood schizonticidal activities against established P.berghei infection in Swiss al-bino mice compare to that of pyrimethamine and sulphadoxine /pyrimethamine respectively.