This research investigates the effect of silica fume on corrosion resistance of slag cement concrete. Twenty-seven different concrete mixes with various percentages of silica fume were prepared. The variables include, silica fume percentage, water / cement ratio, cementitious materials content (slag cement + silica fume) and coarse aggregate type. The test results showed that the slag cement is the best cement for resisting steel corrosion and the use of silica fume as a partial replacement of slag cement by weight improved considerably concrete resistance and the optimum percentage of silica fume that gives the maximum resistance against corrosion after 6 months of partial immersion in aggressive sea water is 20%. Results have shown that can be improved concrete resistance by decreasing the W/C ratios and increasing the cementitious materials content. Using of crushed dolomite has a bad effect in steel corrosion resistance compared to gravelly concrete. Keywords: corrosion resistance; slag cement; silica fume.