In general, the importance of the injection process to column chromatography varies directly with the separation efficiency of the chromatographic column; as the efficiency of the column increases, the injection process may become limiting. Over the past few years, a great many papers concerned with injections into open tubular columns have appeared, and many valuable suggestions have been made. In most cases, the validity of those suggestions is confirmed and their usefulness enhanced by considering injection-related phenomena from the viewpoint of recognized chromatographic principles. Injections into large diameter open tubular columns (530 µm i.d.) may pose other problems. Their much larger sample-loading capacities can normally be utilized only by injecting larger amounts, but larger injections impose different requirements on both inlet design and injection technique. As the size of the injection increases, the chromatographic results are strongly influenced by these factors.