Columns having a compact shape are highly desirable in liquid chromatography, allowing better and easier thermostatting. Packing a conventional high resolution liquid chromatography column in its straight configuration, followed by coiling, has not always resulted in a retention of efficiency. We have recently described a novel polymeric packing material, open-pore polyurethane, where high resolution-low pressure liquid chromatography columns are preparedin situ.These columns have been tested in their linear configuration and then coiled to a variety of coil sizes. Using 2.16 mm i.d. stainless steel tubes, coil diameters as small as 2 in. have been examined and no loss of efficiency was detected. This result has not been achieved before with conventional packings. Additionally, it has been shown that these columns may be coupled in series and the total number of theoretical plates may be calculated. This allows a high resolution series arrangement of columns with minimum column space requirements. This is generally not possible with conventional columns because of their high back-pressure.