Among compounds structurally related to L-lactic acid, an attractant for female Aedes aegypti (L.), 17 had activities approaching or better than that of L-lactic acid at least 1 of the 3 concentration levels tested. Active compounds included 2- to 5-carbon aliphatic acids substituted in the alpha position with a hydroxy, oxo, mercapto, bromo, or chloro group. Two β-hydroxy acids and a β-mercapto acid also were active.