The use of High Strength Concrete is increasing largely nowadays due to its unique properties. The addition of pozzolanic materials such as silica fume and nano-silica as a partial replacement of cement in concrete is considered beneficial as it improves its properties and in the same time reduces the amount of CO2 emitted in the atmosphere during cement manufactory. Adding steel fiber to high strength concrete can improve its ductility, toughness and impact resistance in addition to its strength. The effect of adding silica fume, amorphous nano-silica and steel fibers to the concrete mix on its compressive and splitting tensile strengths was considered in this study at different cementitious contents. Amounts used were 10 % of silica fume and 1 % of nano-silica by weight of cement as partially replacing the same amounts of cement. 2 % of steel fiber by weight of concrete was also used. 500, 600, and 700 kg/m3 cementitious contents were used. SEM micrograph images and EDX spectrum were made on some concrete specimens. Specimens were tested at the age of 28 and 56 days. Concrete prepared with silica fume and nano-silica showed larger compressive and splitting tensile strengths than the control mix. Adding steel fibers resulted in further increase in strength with even larger percentage in the case of tensile strength and this can be related to their ability to control and bridge these cracks.