A polyurethane (PU)-magnetorheological fluid (MRF)/p-aramid fabric composite was fabricated, and its mechanical properties were subsequently investigated. The contribution of the PU-MRF matrix to the impact resistance of the system was then discussed. MRFs consist of stable suspensions of magnetite particles within a carrying fluid. Therefore, when an external magnetic field is applied, the MRFs exhibit drastic and reversible changes in rheological properties as a result of the field-induced ordering of the particulate phase. We then attempted to develop new and enhanced bulletproof materials by incorporating MRF and PU in a p-aramid fabric. It was found that when a magnetic field was applied, the mechanical properties of the PU-MRF/p-aramid fabric composite improved. It was also found that adding a PU matrix improves the impact performance of the PU-MRF/p-aramid fabric composite, relative to a neat p-aramid fabric and a MRF/p-aramid fabric composite with similar areal density. The improved impact performance of the PU-MRF/p-aramid fabric composite appears to be because the PU film and MRF enable different energy absorbing mechanisms, including particle friction, fabric/matrix debonding, matrix cracking, and delamination, which are not observed in neat p-aramid fabric systems. The findings of this study are thought to be important from a design viewpoint of soft armors. POLYM. ENG. SCI., 55:729-734, 2015. (c) 2013 Society of Plastics Engineers