Microbore columns were investigated for their application to High Performance Liquid Chromatography. Microbore columns consist of stainless steel tubing, 1/16¹¹ OD x 1mm ID, packed with silica gel or other suitable material. These columns were evaluated in terms of extra-column variance effects, mass sensitivity, and solvent consumption. Three methods of extracting the extra-column variance effects were evaluated. When used with an instrument whose contribution to total peak variance is small compared to the column, microbore columns provide the best performance for analyses where sample is limited or where reduction of solvent usage is desirable. A method from the literature for extracting extra column variance effects was found to be easy and reliable. It is proposed as a useful way of allowing column performance to be compared from instrument to instrument and for determining whether a particular instrument is suitable for use with microbore columns. / M.S.