Bean (Phaseolus vulgaris L.) with regard to large caloric intake and protein contents ranks next in importance to cereals and potato. The major bacterial diseases including common bacterial blight ( Xanthomonasaxonopodis pv. phaseoli ), halo blight ( Pseudomonassavastonoi pv. phaseolicola ), and bacterial wilt ( Curtobacteriumflaccumfaciens pv. flaccufmaciens ) are three commonly occurring bean diseases worldwide which have the potential to causesignificantyield losses through foliage blight and wilting disorders.In recent years, rapidly spreadingoutbreaks of foliage blight and wilting has been developed in bean fields of Iran, although their causative agents have not been clearly determined. To investigate the causal pathogens of bean blight and wilting, a survey was conducted in bean fields of Lorestan, Hamedan and Markazi provinces during 2013-2014. Of the samples collected from commercial fields located in these regions, total of 57 bacterial isolates were recovered on general and semiselective media. According to their morphological, serological and molecular characteristics, the isolates were categorized into three distinct groups. The Bacterial strains in group I were Gram-negative with translucent yellow colonies which are identified as Xanthomonasaxonopodis pv. phaseoli (Xap) based on biochemical and serological properties. The isolates also produced a 730bp DNA fragment in PCR reaction using specific primer pair (X4c-F / X4e-R) for Xap. The bacterial strains in group I was not able to diffuse melanin pigment in the culture and failed to amplify a DNA fragment with specific primer pair (Xf1/Xf2) for Xanthomonasfuscans su. fuscans, confirming the identification of strains group I as Xap. The Gram-positive bacterial representatives in group II formed creamy yellow colonies on Nutrient Agar medium and produced a 306 bp DNA band in PCR reaction using specific primer pair (Cff-For2 / Cff-Rev4 ) for Curtobacteriumflaccumfaciens pv. flaccufmaciens (Cff). The biochemical test also support the findings that the isolates group II belonged to Cff. The most isolates of Cff were appeared yellowish (carotenoid pigments )and pink on Nutrient Broth Yeast (NBY) medium All the strains Partial amplification and sequence analysis of the 16S rDNA of this isolate with primer Ps-For / Ps-Rev also revealed that the strain is identical to P. viridiflava . After confirming the presence of Cff and Xap as the main causal agents of bean foliage blight and wilting, a multiplex PCR was performed using X4c-F / X4e-R and Cff primers for the simultaneous detection of Xap and Cff bacteria in the infected leaf and seed materials. In all the samples subjected to multiplex assay, a 306 bp band specific for Cff observed along with a 730bp band specific for Xap. The data obtained in the present study reveals the occurrence of both foliage blight and wilting diseases in bean fields of Lorestan, Hamedan and Markazi provinces caused by Xap and Cff respectively. Since both of the pathogens are transmitted by seed lots, multiplex PCR assay could be a reliable and sensitive method for determining whether or not seeds are infected with these pathogens. Key words : Bean, Xanthomonasaxonopodis pv. phaseoli , Curtobacterium flaccumfaciens pv. flaccufmaciens, Pseudomonas viridiflava, Mutiplex PCR