About 2% of commercial kidney bean seed (variety Topcrop) were found to be infected with the charcoal rot pathogen, Macrophomina phaseoli (Maubl.) Ashby, and an average of 6 viable microsclerotia were detected in the contaminated dirt per 100g of these seeds. The field soil of the commercial seed producing area was assessed to contain an average of 11 viable microsclerotia per g of air-dried soil, and kidney bean plants grown in the soil became infected under greenhouse conditions.Pathogenicity test of a total of 6 isolates, 2 each from seed, soil, or contaminated dirt of seed showed that soil isolates were a slightly more pathogenic than others. An average rates of disease incidence (from diseased plants, M. phaseoli was always reisolated) of these 6 isolates were 21.9% at the temperature of above 30°C, and 10.5 at 26°C. Infection rates including visually healthy plants with M. phaseoli-reisolation were 32.2% above 30°C, and 21.0% at 26°C.M. phaseoli present in commercial seed and field soil has a potential ability to become virulent pathogen under favourable conditions.