Abstract The stress influence on the defect production rate and size distribution of defect clusters in cascades was evaluated by molecular dynamics method. Stress was applied by exerting uni-axial, hydrostatic and isometric strain into the cell. For the uni-axial case, strain was varied between −1% and 1%. Defect production rate in cascade increased significantly under uni-axial tensile stress, and even under uni-axial compressive one. The largest increase of defect production rate was observed under isometric strain, and not so much under hydrostatic one. These results indicate that deformation anisotropy is a key factor to increase defect production rate. It was also found that larger defect clusters were formed under the strain condition in which defect production rate is higher.