Abstract The vaccinia virus complement control protein (VCP) blocks classic and alternate complement pathways by binding to the third and fourth complement components and by blocking the formation of the C3-convertase as well as by accelerating the decay of the C3 and C4 convertase. The therapeutic potential of VCP has been extensively studied for brain injury, xenotransplantation, Alzheimer's disease, and spinal cord injury. We investigated the pharmacokinetic behavior of rVCP in mice. Dosage of rVCP was studied by injecting different concentrations of rVCP. A 25 mg/kg or greater dose injected intraperitoneally was found to be adequate to suppress complement for more than 8 hours.