A new bacterial disease was detected on mung bean crops in 1984 in central and southern Queensland. The symptoms were marginal and interveinal necrosis of the leaves with vascular browning in a small percentage of affected plants. No wilting was observed. The same symptoms were later detected on cowpeas in southern Queensland. Disease incidence in the commercial crops of mung bean and cowpea surveyed, ranged from leaf symptoms on an occasional plant to 5°/o-8°/o of the crop affected. However, disease incidence as high as 90% has been reported from other districts. The disease appeared to be most severe in rain-grown crops suffering from moisture stress. The pathogen was identified as Curtobacterium flaccumfaciens subsp. flaccumfaciens on biochemical tests and host pathogenicity. It was shown to be seed transmissible by artificial seed inoculation and pathogenic to soybean and French bean but not to tomato. A toxin was involved in pathogenesis.