Abstract The solvent crack growth of rubber compounded with various carbon blacks or calcium carbonate was investigated. It was found that the rate of crack growth of filler-loaded rubber was linearly related to extension ratio in a manner similar to gum vulcanizates. The rate of crack growth passes through a minimum as the filler loading is increased. It is dependent on the particle size of the filler; smaller particles show much greater effect than coarser ones. When the rates of crack growth of highly loaded samples were plotted against the extension ratio, plots consisting of two straight lines with a bending point were obtained. It was found that the extension ratio at the bending point depended upon the loading and particle size of filler. It was a linear function of the square root of the distance between filler particles. The slope of the line above the bending point varies with type of filler: with carbon black the slope is steeper; with calcium carbonate it is less steep.