The low temperature GeI2 disproportionation reaction was used to grow epitaxial germanium at 350°C selectively in small areas on germanium and GaAs substrates. Germanium deposition rates on masked surfaces were as much as 80 times greater than those observed on unmasked surfaces under the same growth conditions. Enhanced growth rates were more pronounced on (110) surfaces compared to (111) surfaces. Extremely fine line epitaxial structures (0.5 ώm) were obtained which were exceptionally free of spurious overgrowths on the oxide masks. © 1971 The Metallurgical Society of American Institute of Mining.