Germanium nanowires are synthesized in bulk quantities and high purity using a simple vapor transport process. X-ray diffraction, scanning electron microscopy and transmission electron microscopy studies show that these wires are single crystalline with [111] growth direction; they have diameters ranging from 5 to 300 nm, and lengths up to hundreds micrometer, With brief vacuum thermal treatment, the average diameters of the wires can be further reduced to 16 nm.