A number of laboratory tests are useful in the screening of clinical poputations for possible drinking problems. These tests can confirm excessive drinking in situatt6ns where this is suspected but denied. Negative results do not rule out the possibility that excessive drinking is a problem and false positives do occur. No one test is foolproof on its own. A combination of tests should detect over 80% of patients with alcohol misuse. These tests should be interpreted in the light of available clinical information and physical examination. The value of available screening tests will be reviewed. Sensitivity, cost, acceptability will be discussed with a particular focus on GGT and %CDT.