Leaf and stem explants of Brassica juncea cv. Pusa Bold produced callus tissue and plantlets on Murashige and Skoog medium at 18 °C. Among the various organs of inflorescences, systemically infected with Albugo candida explants from hypertrophied peduncles and thickened terminal leaves proved suitable for the production of dua cultures of the biotroph and its host, success with the former being better than with the latter. Dual cultures were also established from ovaries, but poorly. Infected callus grew faster than its healthy counterpart. Leaf and sten pieces with rust pustules did not form callus. The dual culture showed abundant coenocytic intercellular mycelium with spherical haustoria within host cells. Infected callus maintained at 15 and 20 °C for 20 to 30 d showed only sporangial chains that remained confined within the callus tissue, whereas callus maintained at 25 and 30 ° contained both sporangia and oospores, like those of A. candida found in naturally infected tissues. The pathoge could be maintained in infected callus tissue for prolonged periods by periodic subculturing and it kept pace with the growth of the callus tissue. Placement of an infected callus in close contact with a healthy one did no result in infection of the latter.