Vaccinia virus complement control protein (VCP) is an immunomodulator that inhibits both the classical and alternate pathways of the complement system, therefore preventing cell death and inflammation. VCP has previously been shown to be therapeutically effective in mild and moderate traumatic brain injury models. In this study the efficacy of VCP in a severe head injury model is investigated in Wistar rats. Training in a Morris Water Maze (MWM) commenced 2 days prior stereotaxic surgery. Rats were anesthetized before being subjected to a severe (2.7-3.0 atm) lateral fluid percussion injury (FPI) 3.0 mm lateral to the sagittal suture and 4.5 mm posterior to bregma. Ten microliters of VCP (1.7 microg/microl) was injected into the injury site immediately after FPI. Fourteen days post-FPI, rats were tested for spatial learning and memory using the Morris Water Maze, followed by a battery of sensorimotor tests. The latter tests showed statistically significant differences between saline-treated and VCP-treated rats in lateral left pulsion (p=0.001) and tactile placing (p=0.002) on the first 5 days of testing. In addition, significant differences in right lateral pulsion in the first 4 days (p=0.007) of testing was evident. The results suggest that in a severe head injury model, VCP at this dosage favorably influences sensorimotor outcome.