Techniques for the emergency control of adult Aedes aegypti populations and their development are reviewed. Larviciding and environmental measures provide only delayed control of adult populations. Large-scale field trials of the ultra-low volume application of insecticide concentrates in Southeast Asia, South America and Africa, using aerial, ground, vehicle-mounted and hand-carried equipment, have, in most cases, resulted in satisfactory levels of control of adult populations. Sequential or indoor ULV applications of fenitrothion have provided immediate control and sustained reduction of the adult populations, often lasting well through normal peak transmission periods of dengue. Many ULV application trials in the Caribbean have not produced satisfactory control, but it is considered that this was due to the type of house construction, to the lower dosage rates of the malathion 96% ULV concentrates used, or to inappropriate droplet sizes. While ULV applications can provide rapid and effective emergency control of vectors at the time of outbreaks of disease in urban and periurban areas, they should not be used as a routine mosquito control measure nor as an alternative to reducing vector populations by environmental measures.