In the field of gas chromatography, the employment of micro-bore columns is probably the most effective way of increasing analysis run-times.It is well-known, in fact, that the reduction of the column internal diameter limits band broadening, thus enhancing separation power.The main advantage is that capillary lengths may be shortened while resolving power is essentially maintained if compared to conventional columns.Present-day very fast GC analyses (60-180 sec time ranges) are generally carried out by using 10 m×0.1 mm I.D.micro-bore capillaries.In order to achieve such rapid elution times the latter are operated under rather extreme and far-from-ideal experimental conditions.The present research is focussed on the evaluation of the use of a short segment of 0.1 mm I.D.micro-bore column, operated under ideal or near-to-optimum conditions, in very fast GC analyses.Complex representative samples were initially rapidly separated on a 10 m×0.1 mm I.D.