Abstract The expression patterns of two muscle-specific actin genes were studied in the yellow fever mosquito, Aedes aegypti. The coding sequence of AeAct-2 exhibits between 82 and 85% similarity with coding sequences of the Drosophila melanogaster and predicted Anopheles gambiae actin genes. The transcription of the AeAct-2 gene was differentially regulated during developmental stages with higher levels of expression in larvae and lower levels in pupae and adults. The AeAct-2 gene is mainly expressed in the head and body wall tissues. Transcripts of the AeAct-3 gene are not detectable in larvae until late 4th instar and the level increased in male pupae and early male adults. The main site of expression of the AeAct-3 gene was the thoracic tissue. Thus, AeAct-3 is the first reported male-specific actin gene in mosquitoes.