The effect of native and recently introduced natural enemies of the cassava mealybug Phenacoccus herreni Cox & Williams in northeastern Brazil is reported in this article. Studies of population fluctuation of the mealybug and its natural enemies were conducted between 1994 and 1997 in three cassava fields located in Muritiba, Itaberaba, and São Gonçalo, State of Bahia. At least ≈85% of the parasitoids found in those fields were composed of the recently introduced species Apoanagyrus (=Epidinocarsis) diversicornis (Howard), Aenasius vexans (Kerrich), and Acerophagus coccois Smith. A. diversicornis was found in all fields during most of the experimental period, whereas A. coccois and A. vexans were only found in the fields where they had been released. A. diversicornis out-competed A. vexans in São Gonçalo, but not A. coccois in Itaberaba. Most predators collected belonged to the genera Hyperaspis, Nephus, and Diomus, all of the family Coccinelidae. The results of this work suggest that the concerted action of the three introduced parasitoids and the native natural enemies was sufficiently efficient to control P. herreni at low levels, in the fields where the study was conducted.