Proteomic is now increasingly considered as useful technique to reveal genetic diversity among different bacteria isolates differentiating live pathogens from dead ones. This book, therefore, reveals proteomic diversity of thirty Xanthomonas oryzae pv. oryzae (Xoo) isolates, the causative agent of rice bacterial leaf blight disease in West Africa, using isozyme polyacrylamide gel electrophoresis (PAGE) analysis. The study revealed 23 isozyme loci in which SKDH produced 33.3-93.3 % polymorphism, EST and G6PH equally gave 40-96.7 % polymorphism within the Xoo isolates enzyme profile. Phylogenetic relationship among 30 Xoo isolates revealed two major genetic groups (Xoo-A and Xoo-B) with two subgroups each (Xoo-A1 and Xoo-A2) and (Xoo-B1 and Xoo-B2). The distinct pattern of each isolate suggested high level of genetic variation and frequent occurrence of mutants in Xoo isolates in different host cells. This information should especially be useful for rice breeders, rice pathologists, rice disease epidemiologists, rice biotechnologist and the scientific community aiming at development of durable Xoo resistant rice cultivars to different localities in West Africa.