Mango is one of the important economic fruits in Taiwan, and Mango Bacterial Black Spot (MBBS) is a limiting factor for mango industries. We isolated and identified the bacterial pathogen, investigated the susceptibility of 'Taichung No. 1' and 'Irwin' cultivars to MBBS and surveyed the disease severity in order to understand the effect of MBBS on the production of the two cultivars. Xanthomonas citri pv. mangiferaeindicae strain Tcpb10 could infect the mango cultivars 'Taichung No. 1' and 'Irwin' showed that the cultivars were susceptible to MBBS. The field survey found that the disease severity of 'Taichung No. 1' was higher than 'Irwin'.