Growth and conidiogenesis of the (+) IMI 101 693 and (-) IMI 101 695 strains of Trichophyton simii were compared at several temperatures (20 to 40 degrees C) and various pH (pH 4 to 9) and were correlated with the concentration of glucose (20 to 100 g/l) or other glucidic substrates (10 g/l). Although the development of both strains was optimal between 25 to 33 degrees C at pH 6 and with 10 g/l of glucose, the (-) strain always growed less than the (+) strain. Conidiogenesis was inhibited by sucrose in the (-) strain and by lactose in the (+) strain.