To gauge the extent of mosquito problems and their impact on local people in Thailand, a simplequestionnaire was designed consisting of 6 questions with multiple choices to be answered in 4 different communitiesin Thailand in 1998 and 1999. Mosquito biting activity was noted often by respondents. They reportedthat mosquitoes bit both night and day, and that the insects were abundant both in the dry and the rainy seasons.In all 4 communities, a large proportion of the residents used bed nets, mosquito coils, and aerosol sprays forpersonal protection; vaporizing mats and repellents were used sparingly. The cost of such measures amountedto $4 to $25 per year per household. For most of the residents, this represented a substantial proportion of theirincome, and was proportionally greater than the average cost of organized mosquito control in developed countries.This suggests that instituting organized local vector control programs would be cheaper and more effectivethan the individual use of personal protectants that do not reduce mosquito numbers. An assessment of theavailable products stocked in neighborhood stores and supermarkets for personal protection was made. A varietyof insecticidal aerosols, mosquito coils, liquid sprays, vaporizing mats, and vaporizing liquids was stocked. Thisample supply of household insecticides lends support to the preferred methods of protection reported by therespondents. The active ingredients in most of the formulations were synthetic pyrethroids, although a fewcontained dichlorvos, propoxur, and a few other compounds. Mosquito coils, the most preferred products usedby the poo! were evaluated for efficacy, and were found to provide a reduction of 72-96Va in landing-bitingrates in controlled experiments.