Light figures revealed by Ge single crystal surface etched with various chemical reagents are examined if they are applicable to the determination of crystal orientation. The figures are analyzed and the structures of the etched surface are observed under microscope, from which information regarding the revealed crystal face is obtained. Distinct light figures suitable for the orientation work are obtained by a short-time etching with concentrated nitric acid plus water plus hydrofluoric acid plus silver nitrate (45 cc+45 cc+10 cc+50 or 20mg or 20 cc+40 cc+40 cc+2g), with hydrofluoric acid plus hydroperoxide plus water (1 : 1 : 4), and with hydroperoxide (100°C). Among these etchants, hydrofluoric acid plus hydroperoxide plus water (1 : 1 : 4) is most suited for accurate orientation determination. Generally, the crystal faces developed by etching are found to be those belonging to the principal crystal zones, but dilute nitric acid heated at 70C° gives some additional high indexed crystal faces belonging to a high indexed crystal zone. There is a tendency that low-index crystal faces appear by a short time etching and high-index ones by a prolonged etching. It is to be added that relatively chear light figures are obtained on germanium crystals, as polished with SiC powder.