This presentation reviews two aspects of the injection of large samples in GC. In terms of best resolution, the band width of the sample at the inlet should not contribute significantly to the band width at the column exit. A reasonable requirement for isothermal chromatography is that the sample injection volume for a component should not exceed V/2√n, where V is retention volume and n is the theoretical plate number. In programmed temperature GC, the significant quantity is not the retention volume, but the retention volume a component would have if it were to be eluted at the initial temperature. Thus, the time for sample injection and the time for analysis can be largely under independent control. Low temperature combined with large volume or long-time sample injection techniques are important in trace analysis. The effect of using large samples on retention volumes is interpreted in terms of Raoult's law.