Compared with most illicit drugs, alcohol rapidly disappears from the body and its metabolites are equally short-lived. Because of this, monitoring alcohol use generally requires indirect techniques. These rely on the fact that alcohol has toxic effects on various organs or interferes with various metabolic processes. The enzymes most closely associated with alcohol abuse can easily be measured in blood samples. The only way of detecting low levels of consumption is to use either an external device that detects alcohol in sweat or a complicated and expensive chemical test, which can detect even moderate amounts of alcohol consumed with the previous 48 hours. Most illicit drugs are relatively easy to detect even 2 or 3 days after they were last consumed. The tendency is to concentrate on detecting the use of illicit drugs rather than their abuse or excessive use. The problem with random urine tests is that they are qualitative rather than quantitative. Hair analysis is much more useful in indicating changes in the consumption of a particular drug on a month-by-month basis. Abstinence-based treatment (ABT) includes nonpharmacological techniques as well as pharmacological interventions to improve abstinence rates, such as Antabuse. But the relapse rates with ABT are often high. Some practical advantages of hair vs. urine testing are the ease of invasion, its usefulness in preparation of medicolegal reports, success in treating and monitoring addicted doctors and other health professionals, and usefulness as a measure of compliance with methadone maintenance treatment. Hair analysis can clarify a diagnosis in unadmitted illicit drug use in a severely mentally ill patient. Some anomalous results can occur in hair analysis. Where the dispute involves evidence of use in the previous month, testing pubic or axillary samples may help to resolve claims of contamination. 27 references