The house rat,Rattus rattus is the most predominant commensal rodent pest worldwide.In addition to damaging food grains in transit and storage,it also acts as reservoir of a number of diseases of man and livestock.Plant based non-lethal repellents are most suitable for rodent control.Citronella oil has been considered as a non-toxic biopesticide.During the present study,mature and healthy house rats (n=6 of each sex) were exposed to 5,10,and 20%concentration of citronella oil applied as a spray and within encapsulated wax blocks in laboratory pens daily,every second day or once per week in bi-choice tests.The repellent effect of the oil was assessed based on food consumption from treated and untreated sides for four days.Overall,food consumption was significantly (P<0.05) lower from the treatment side compared to the untreated side indicating a significant repellent effect of the oil.This repellent effect was similar for both males and females.The percent repellency was greater when the oil was applied daily or every second day compared to when applied once per week indicating low persistence of the repellent effect due to the volatile nature of the oil.The present studies reveal the potential of citronella oil as a repellent for R.rattus; however,further studies must be conducted to enhance the persistence of the effect for longer period of time.