This paper presents the results of experimental work on tensile strength of concrete caused by flexure, which is called rupture modulus. The work focused on concrete mixes having water/binder ratios of 0.35 and 0.45, which contained constant total binder contents of 500 kg/m3 and 400 kg/m3, respectively. The concrete mixes contained four different kinds of superplasticizers with and without silica fume. The percentage of silica fume that replaced cement in this research was 10%. Based upon the experimental results, the ACI 318-89 (92) equation for anticipating the rupture modulus of concrete according to its compressive strength was exact enough and also on the safe side.