A simple and rapid liquid chromatographic method for the determination of atenolol in plasma is described. Plasma proteins were precipitated with zinc sulphate and sodium hydroxide prior to injection onto a precolumn, which was connected to the analytical column by a switching valve. When atenolol was eluted onto the analytical column, the precolumn was cleaned by backflushing to eliminate strongly retained endogenous compounds. The atenolol fluorescence was measured after excitation at 197 nm. The limit of quantitation in plasma was 15 ng/ml. The within-day precision of atenolol was 1.6% at a level of 210 ng/ml, 5.0% at 25 ng/ml and the between-day precision was 3.3% at 50 ng/ml.