This paper presents the experimental results of the long-term mechanical properties of silica fume high strength mortar (SFHSM). Nine mixes were carried out in this study; one mix without S.F used as a reference, four mixes with S.F used as a partial replacement and four mixes with S.F used as an addition. The S.F percentage ratios used were 5, 10, 15, and 20 % of the cement weight. In all mixes the water/cementitious materials ratio was kept constant at 0.40 and the sand : cementations materials ratio was 3:1. The long-term properties were obtained by using the accelerated ageing procedure. The accelerated long-term specimens were cured in 100% relative humidity at room temperature for 28 days then in 60oC hot water till tested at 10, 30, 50, 70, 100, and 120 days. This regime was used earlier in the literature on Glass fiber reinforced concrete (GRC) and it was found that it was equivalent to 1, 3, 5, 7, 10, and 12 years, respectively, of its exposure to natural weathering in Egypt. The experimental results showed a slight gradual increase in the compressive strength, indirect tensile strength, and flexural strength of SFHSM on the longterm as compared to the short-term results followed by a small reduction in the strengths after a certain age. S.F mortar specimens having 10% S.F as a partial replacement of cement weight showed about 9, 22, 16 % increases in the compressive, indirect-tensile, and flexural strengths, respectively, of those of 56 days strengths after 70 days immersion in hot water, followed by a small reduction of about 8, 6, and 5 % in the compressive, indirect-tensile, and flexural strengths, respectively, at 120 days in hot water.