The brain and subesophageal ganglion of male Aedes aegypti (L.) (Diptera : Culicidae) are described from cryofractures and silver-stained, semithin (0.5 μm) serial sections of whole heads observed in the scanning and light microscopes. The brain and subesophageal ganglion of male A. aegypti are fused. The major structures of the brain include the protocerebral lobes and bridge, the mushroom bodies, central complex of the protocerebrum, the mechanosensory regions and olfactory loves of the deutocerebrum, and the tritocerebrum. Major commissures of the brain are the anterior optic tract, central commissure, posterior dorsal commissure, and subesophageal commissure. The structural associations of brain components with each other and the subesophageal ganglion, as well as the paths of the major nerve tracts in male A. aegypti are described and compared with those in other Diptera.