We have investigated the structural stability of the ternary Zintl phase LiInGe up to 35 GPa by means of angle dispersive X-ray powder diffraction. At ambient conditions LiInGe crystallizes in a cubic facecentred structure consisting of a polytetrahedral arrangement of In and Ge atoms. The compound undergoes a reversible phase transition to an X-ray amorphous high pressure modification between 20 and 30 GPa. We have determined the equation of state for the low pressure phase and the result is discussed with respect to the related binary NaTl-and zincblendetype compounds. In order to investigate the electronic properties of LiInGe we have performed LMTO band structure calculations.