ABSTRACT.We report the successful introduction of heterologous DNA sequences into embryos of the mosquitoAedes aegypti(L.) by microinjection. The injected DNA carrried P transposable element sequences, derived from and known to facilitate transformation inDrosophila melanogaster.Two plasmids, one of which carried a dominant selectable marker, were introduced into the posterior of embryos prior to pole cell formation and subsequently taken up into the germ line of transformed individuals. Stable transfer of the selectable marker (G418 resistance) was demonstrated over two generations. The precise nature of these putative P mediated integration events is currently being investigated. However, the results presented here establish the technique of DNA transformation for the genetic manipulation ofAedes aegypti.