Transpiration cooling of the inside of a pipe was studied. The problem was attacked by conducting a literature search, analytically and numerically solving the problem, and by experimentation. Several publications were identified as providing either numerical or analytical results relevant to transpiration cooling inside a pipe. An analytical comparison of regenerative wall cooling and transpiration cooling was conducted. The results show that the hot side wall temperature is related to the flow characteristic Biot number for the regenerative case and Stanton number for the transpiration case. A numerical finite difference model was developed and analyzed to determine how injecting a fluid into a porous pipe with fully developed flow effects Nusselt number. Comparison was made for the injection Nusselt number to the Nusselt number of Poiseuille flow. Convection heat transfer coefficient measurements for transpiration cooling of a porous pipe were conducted. The results suggest that this cooling method can be effective in providing heat protection to porous materials.