Ointment and cream formulations of lemongrass oil in different classes of base and the oil in liquid paraffin solution have been evaluated for mosquito repellency in a topical application. Mosquito repellency was tested by determining the bite-deterrence of product samples applied on an experimental bird's skin against a 2-day starved culture of Aedes aegypti L. mosquitoes. The 1%v/v solution and 15%v/w cream and ointment preparations of the oil exhibited > or =50% repellency lasting 2-3 h, which may be attributed to citral, a major oil constituent. This activity was comparable to that of a commercial mosquito repellent. Base properties of the lemongrass oil formulations influenced their effectiveness. The oil demonstrated efficacy from the different bases in the order of hydrophilic base > emulsion base > oleaginous base.