Body size may be strongly related to physiological status and reproductive success in insects. Intraspecificsize variations in Aedes albifasciatus Macquart, Aedes crínifer (Theobald), Culex dolosus Lynch Arribál/aga,Culexpipiens L. and Psorophoraferox Humboldt females, were quantified in order to test the hypothesis thatincreased body size is related to increased parity in field populations of these mosquitoes. Host-seeking adultswere collected every fifteen days in Punta Lara and La Plata, Buenos Aires, Argentina, with C.D.C. trapsfrom September 1990 to August 1991. Wing lenght was measured in all mosquitoes. Physiological status wasdetermined according to ovarían tracheation. Size variation was high, and the seasonality of mean winglenght showed an inverse relationship with temperature. No evidence of increased reproductive success inlarger individuáis was found. Therefore, it was unable to demónstrate that large-bodied females of the specieshave increased fitness than small ones.