Stimulation of growth by Rhizoctonia solani with the formation of infection cushions as a response to root exudates was reported by many authors (KERR 1956, FLENTJE et al 1963, WYLUE 1959, DODMAN and FLENTJE 1970), In 1968 a correlation between the type of infection cushions formed by R. solani and the mode of fungal penetration into host tissues. They introduced evidence that induction of dome-shaped infection cushions was followed by a direct penetration with or without penetration pegs, while formation of lobate appressoria preceeds penetration through stomata.According to MITCHELL (1976), investigations in this area were unable to confirm a correlation between susceptibility to infection and a selective stimulation by exudates of susceptible tissues.This investigation was carried out to confirm a correlation between susceptibility or resistance of cotton seedlings to R. solani and the selective formation of different types of infection cushion-like structures as a response to root exudates of susceptible or resistant plant tissues. Materials and Methods (A) Inoculations of plantsFour Egyptian cotton cuitivars (Giza 67, Giza 68, Giza 69 and Giza 75) were used as test plants. Seeds were germinated on wet filter paper in dark at 30 °C. After 72 h, seedlings U.S.