Our objective was to evaluate the hemostatic efficacy of a newly modified chitosan in a porcine grade V liver injury model. Fifteen Yorkshire pigs underwent standardized grade V liver injuries with a specially designed liver clamp and were randomized to either modified chitosan (MC) patch treatment or standard gauze packing. Free bleeding was allowed for 30 seconds. Fluid resuscitation was infused as necessary to reestablish a mean arterial pressure (MAP) within at least 80 per cent of the preinjury MAP. Animals were observed for 90 minutes or until death. Endpoints were survival, total blood loss, time to hemostasis, and resuscitation MAP, and resuscitation volume. Total mean blood loss was less in the MC patch group (464 +/- 267 mL vs 1234 +/- 78 mL, P < 0.001). Time to hemostasis was significantly less (4.8 +/- 2.5 minutes in the MC patch group vs 9.6 +/- 2.5 minutes, P < 0.01). Fluid resuscitation was less (1098 +/- 459 mL in the MC patch group vs 1770 +/- 172 mL, P < 0.01). Survival was 100 per cent in the MC patch group and 80 per cent in the gauze packing group. MC patches demonstrate the continued hemostatic agent evolution for improved control of lethal solid organ bleeding.