and much used anti tuberculosis drug. The mesoporous silica nanoparticles were prepared by using tetraethyl ortho silicate and cetyltrimethyl ammonium bromide [as surfactant] . The prepared nanoparticles were characterized in terms of their particle size measurement and porosimetry. The results showed that the particle size is 218 +/- 46 nm [mean +/- SD] and surface area is 816 m [2] g [-1] . In order to load rifampin within the mesopores, adsorption experiments using three different solvents [methanol, water and dimethyl sulfoxide] were carried out. The loading procedure resulted in a significant improvement in the amount of rifampin loaded into mesoporous silica nanoparticles and methanol was found to be a suitable solvent, providing a drug entrapment efficiency of 52 %. Rifampin loaded nanoparticles underwent different in-vitro tests including, SEM and drug release. The in-vitro drug release was investigated using buffer phosphate [pH=7.4] . Regarding the drug release study, a biphasic pattern of release was observed. The drug-loaded mesoporous silica nanoparticles were capable of releasing 95% of their drug content after 24 h, following a faster release in the first four hours. The prepared rifampin loaded nanoparticles seem to have potential for use as a pulmonary drug delivery