Aim of the study: To compare the antibacterial effect of Nano-calcium hydroxide ( Nanostreams, Cairo, Egypt)  mixed with saline versus conventional calcium hydroxide (GAMA dental lab,Cairo, Egypt) with saline and calcium hydroxide paste with iodoform (Cal plus) (Apexion, Karala, India) against E-faecalis using agar diffusion method. Samples were classified into 3 groups according to the material used. Each group was further divided into 3 subgroups according to the observation time (1day, 3days and 7 days). Each group consisted of 7 agar plates implanted with E-faecalis strain. 3 holes were created in each agar plate, each hole contained one tested material. The results showed that Nano calcium hydroxide had the largest inhibitory zone of E faecalis in agar diffusion test over all observation periods followed by conventional calcium hydroxide. The calcium hydroxide mixed with iodoform had the least average inhibitory zone. Calcium hydroxide Nano particles have superior anti microbial activity against E faecalis compared to other tested materials.