In this study we evaluated and reported repellent effects of essential oils from Thai plants against 4 mosquito vectors: Aedes aegypti, Ae. albopictus, Anopheles. dirus and Culex quinquefasciatus under laboratory conditions using human volunteers. The essential oils were extracted from 18 plant species, belonging to 11 families, and the oils were then prepared as 10% solution in absolute ethanol with additives. Two chemical repellents, deet and IR3535, were also prepared in the same formulation as the essential oil repellents and tested for repellency as controls. The essential oils were also evaluated for oviposition deterrent effects against Ae. aegypti under laboratory conditions. The results show night-biting mosquitoes (An. dirus and Cx. quinquefasciatus) and Ae. albopictus were more sensitive to all the essential oils (repellency 4.5 - 8 hours) than was Ae. aegypti (repellency 0.3 - 2.8 hours), whereas deet and IR3535 provided excellent repellency against all four mosquito species (repellency 6.7- 8 hours). All essential oils exhibited oviposition deterrent activity against Ae. aegypti with various degrees of repellency ranging from 16.6 to 94.7%, whereas deet and IR3535 had no repellency. The present study demonstrates the potential for using essential oils as mosquito repellents and oviposition deterrents. These findings may lead to new and more effective strategies for protection from and control of mosquitoes.