The role of transmission electron microscopy (TEM) in failure analysis of semiconductor ICs will be discussed. Discussion will include basics of TEM imaging techniques, origin of different image contrast mechanisms, and image interpretation procedures for failure analysis integrated circuits. A brief review of energy dispersive spectrometry (EDS), electron energy loss spectrometry (EELS), scanning transmission electron microscopy (STEM), and their applications in failure analysis will be presented. Site specific TEM sample preparation techniques suitable for failure analysis of ICs will be described. New developments in the area of TEM cross-section and planar sample preparation using FIB milling will be reviewed. Finally, several applications of TEM in failure analysis will be discussed using a number of examples from case studies of defects in silicon, gate oxide breakdown, interfacial reaction, and poly stringers.