A study of the 4 subspecies in the Aedes atropalpus group was conducted using acrylamide gel electrophoresis to separate soluble proteins. Four anodically migrating protein bands were observed in whole-body homogenates of each subspecies. Differences in rates of migration and staining intensities of the protein bands were sufficient to differentiate the subspecies. Therefore, the biochemical data tend to support the 4 subspecies rather than the 2 species concept of the group.