The relative susceptibilities of certain rice varieties to infestation with the rice stem borer Chita agamomnon Bles. and rice leaf miner Hy-drellia prosternalis Deem .was studied in field experiments carried out in 1997 and 1998 at Serw, Damietta Governorate, for two successive rice growing seasons. 1.Monitoring the resistance or rice varieties against the rice stem borer Chilo agamemnon Bles: Rice varieties differ in their susceptibility or resistance to the infestation by the rice borer at dif‌ferent stages of rice plant growth. Sakha 101 and Sakha 102 were the least susceptible in the tellering stage than in the flowering stage 2.2 and 2.8 to 3.8 and 5.0, respectively. Giza 178, Giza 176 and Giza 181 demonstrate moderate infestation levels, while Giza 177, Giza 175 and Giza 11 were comparatively high susceptibility. 2.Role action (preferendum) and reflex action (antibiosis) be-tween rice varieties to Infestation and Hydrallia prosternal‌is Deem infestations: Tested rice varieties were classified accord‌ing to damage leaf into the following three groups: a.Less susceptible: Giza 177, Giza 178 and Giza 175, mean infestation were ranged between with an average of 54 % b.Moderately susceptible: Sakha 102 and Sakha 101, mean infestation averaged of 76 %. c.Highly susceptible: Giza 178, Giza 181 and Giza 176, mean infestation with an average infestation of 86%.