The development of modern capillary GC inlet systems is reviewed, and the principal types of inlet are classified according to sample flow and thermal conditions during injection. Recent developments in direct injection onto 530-µm i.d. columns are examined. The application of programmed-temperature injection to high-temperature capillary GC columns is demonstrated for solutes up to n-C100. The useful molecular-weight range of capillary GC can be extended into regions previously covered only by liquid chromatography or supercritical fluid chromatography by the use of high-performance capillary inlets in combination with high-temperature columns.