Mango (Mangifera indica L.) is cultivated throughout the tropics as well as in subtropical areas and suffers from a number of diseases caused by bacteria, fungi and other agents.Because no efficient chemical control is available, mango bacterial black spot (MBBS;synonym mango bacterial canker) caused by Xanthomonas campestris pv.mangiferaeindicae (Xcmi;synonym X.citri pv.mangiferaeindicae) is a recurring limiting factor for mango industries in the Old World.The movement of infected, asymptomatic leaf, branch and fruit is a major means of pathogen dispersal.A reliable and sensitive diagnostic procedure is necessary for the safe movement of mango planting material.A set of primers based on the partial sequence of the hrpB gene was designed to develop a PCR assay for this pathogen.Primer pairs (XcmiHF and XcmiHR), which amplified a single specific band of 321 bp,were tested for specificity and sensitivity in detection DNA and cell from Xcmi.Amplication was positive only with genomic DNA from 12 Xcmi strains, no PCR products were observed with DNA from 10 other Xanthomonads and 7 other bacterial species.The sensitivity of detection was 2.4 pg of plasmid DNA, and 1.8 × 104CFU/mL cell.The primers also worked well for pathogen detection in direct PCR assays of Xcmi colonies grown on liquid medium and in PCR assays of total DNA from leaf, branch and fruit lesions.PCR assays proved to be relatively sensitive and could become very useful in detecting Xcmi in mango planting material.