The broad range of applications of high-performance liquid chromatography (HPLC) in biochemistry and cell biology is demonstrated by the purification of antibodies, separation of glycosidases and isolation of a liver membrane protein with a molecular weight of 65 000-67 000 daltons. The advantage of HPLC over classical chromatographic methods is shown by the purification of the glycosidases from Streptococcus pneumoniae. These enzymes can be purified to a degree similar to what can be achieved by "classical" ion exchange, combined with affinity chromatography, but the time needed for the HPLC experiment is much shorter and the yield at least three to five times higher. Particular attention is directed to sample preparation before HPLC separation. For the best results, a combination of HPLC with other biochemical and immunochemical methods is necessary, as is also demonstrated.