Background: Nanotechnology is used in enhancing some existing materials.Nano-calcium hydroxide sealers are introduced to eliminate the short-comings of the conventional one. Objectives: To evaluate the physical properties of Sealapex incorporated with calcium hydroxide nanoparticles(CHNP). Methods:Calcium hydroxide nanoparticles were incorporated to Sealapex root canal sealer in concentrations of 3% and 8% by weight respectively.Three groups were established: Group I (Sealapex+3%CHNP), Group II (Sealapex+8%CHNP) and Group III (Sealapex in the conventional formula).Solubilitywasevaluatedaccording to ISO standardization 6878:2012 specificationand evaluated at time intervals of (24 hours and 14 days). ForpH assessment, specimens were immersed in deionized water and measured using a pH meter at time intervals of (1, 3, 24 hours and 14 days).Results:Group II (Sealapex+8%CHNP) showed a significantly lowersolubility value at 24 hours and the highest pH value after 3 hours. Conclusions:The addition of 3% CHNP to Sealapex resulted in a negative effect on the solubility of the sealer but enhanced its alkalinity.On other hand, the addition of 8% CHNP enhanced the physical properties of the sealer.Clinical Significance: The addition of nanoparticles to currently existing sealer formulas may enhance its physical properties and eliminate some of its drawbacks.