High performance liquid chromatography with column switching has been developed for the determination of fluconazole in plasma. The plasma samples were injected onto a precolumn packed with LiChromprep RP2(25-40 microns) after simple dilution with a solution of 0.2 mol.L-1 acetic acid. Distilled water was used to wash out protein and other polar components in plasma. After switching, the concentrated fluconazole was eluted in the back-flush mode onto a Shimpack CLC-ODS column with methanol--0.2 mol.L-1 ammonium acetate (pH 2.7) (50:50) as mobile phase. Purge solutions were used for clean-up and for regenerating the precolumn. The method showed a good precision and excellent recovery. The detection limit was 0.12 micrograms.ml-1 plasma. The RSD's (intra- and interday) were less than 6.3%. The method has been successfully used to determine bioavailability and pharmacokinetics of fluconazole in Chinese volunteers.