Percent transmission as well as colony forming units (c.f.u.) per grame of seeds were estimated for Xanthomonas campestris pv. phaseolli in two lots of bean seeds (Cultivars ?EMGOPA 201 Ouro? and ?EMGOPA 202 Rubi?). Percent transmission percent transmission was estimated by planting 200 seeds, individually, in sterile ?tubetts? containing vermiculite. Percent transmission was estimated, for EMGOPA 201 Ouro? and ?EMGOPA 202 Rubï, as being, respectively, 24,0% and 13,5%. A selective medium was developed by adding, to a basic culture medium, antibiotics to which 11 isolates of the pathogen, from differents regions of Brazil, were resistant. Extraction of seed lots followed by planting of the extracts in the selective medium allowed the quantification of bacteria in terms of c.f.u./g of seed. Values of 6.3 x and 1.58 x 108 c.f.u./g seed were obtained, for cultivars ?EMGOPA 201 Ouro? and ?EMGOPA 202 Rubi?, respectively.