During 2006, laboratory studies were conducted to evaluate the pathogenicity of seven isolates of Pandora neoaphidis (Remaudière & Hennebert) against the cabbage aphid, Brevicoryne brassicae (L.). Two isolates were obtained from the aphids Rhopalosiphum padi (L.) (TEXRP1), and Myzus persicae (Sulzer) (TEXMP1), infesting broccoli (Brassica napus (L.)) in Texcoco, Mexico; the rest of the isolates were obtained from Rhopalosiphum maidis (Fitch) infesting sorghum (Sorghum bicolor (L.) Moench), in five localities in Tamaulipas, Mexico. The greatest percentages of mortality were caused by isolates RBF, TEXRP1, y RBB, at a rate of 87, 76, y 72%, respectively, 240 hours after the initiation of the treatments. These results show the potential of P. neoaphidis as an agent of biological control against B. brassicae, depending of the place and the origin of the isolate.