Studies were carried out to evaluate the repellent action of neem oil against Culex quinquefasciatus. Application of 2 and 5 per cent neem oil @ 5 ml/person/night gave 50 and 40.9 per cent protection in indoor collections and 17.4 and 5.6 per cent in outdoor collections as compared with that of untreated control respectively. The protection time ranged from 0100 to 0300 hrs and 0100 to 0600 hrs in indoor and outdoor collections respectively. Results of repellent action of Autan, a synthetic mosquito repellent studied concurrently showed a relatively higher protection rate from the bites of Cx. quinquefasciatus.