This study aimed to evaluate the effect of the addition of the activated charcoal to different formulations of calcium hydroxide on the fracture resistance of endodontically treated teeth. Ninety one freshly human extracted single rooted teeth were selected. The samples were cleaned and shaped and classified according to the type of the dressing into five groups; Group 1; (21 samples) dressed with calcium hydroxide paste with Iodoform ( Metapex) (META,Chungcheongbuk-do,Korea ), Group 2; (21 samples) dressed with conventional calcium hydroxide with saline(GAMA dental lab,Cairo, Egypt ). Group 3; (21 samples) dressed with calcium hydroxide paste with Iodoform mixed with activated charcoal ( Eucarbon Sedico, Cairo, Egypt) and Group 4; (21 samples) dressed with conventional calcium hydroxide and activated charcoal with saline and Group 5; Control group (undressed). The samples were further classified according to the observation time into: Subgroup A; (7 samples) after two weeks. Subgroup B;(7 samples) after one month and Subgroup C; (7 samples) after two month. Samples were loaded vertically after the observation periods using Universal Testing Machine until fracture. The results showed that the fracture resistance of the samples dressed with either Metapex or conventional calcium hydroxide showed lower resistance to fracture than those dressed with either two formulations with activated charcoal. It was concluded that the addition of activated charcoal to the calcium hydroxide compounds can decrease their weakening effect on the endodontically treated teeth.