The effect of microballoon volume fraction on the tensile properties and fracture mode of syntactic foams is characterized in the present research. Two types of glass microballoons, having 220 and 460 kg/m3 density, are used with epoxy resin matrix for making the syntactic foam samples. These foams contain 30%, 40%, 50% and 60% microballoons by volume. Both types of microballoons have the same size but different wall thickness, which reflects as a difference in their density. It is observed that the tensile strength and modulus increases with a decrease in the volume fraction of microballoons in the syntactic foams. The syntactic foams containing weaker microballoons showed lower modulus but higher strength compared to the syntactic foams containing stronger microballoons.