NIJ's 5-year plan for developing the capabilities of hair testing includes supporting the ongoing epidemiological studies, developing laboratory procedures and standards, and establishing the acceptability of hair test results as evidence in court. Much of this research is being conducted by NIJ in collaboration with the National Institute on Drug Abuse. Because hair analysis and urine testing address different time periods of illicit drug use, hair testing should not be expected to replace urinalysis. However, hair testing offers promise as a supplementary technique. Because it detects exposure over prolonged periods of use, it can also be done less often than urinalysis and could potentially reduce program costs. These advantages would make hair testing a valuable part of drug treatment for arrestees, providing the information the criminal justice system needs to place offenders in drug treatment programs and to monitor compliance with program requirements. In several court rulings, the results of hair testing have been found reliable and acceptable as corroborative evidence of drug use. Summary of testing technologies, table, and 11 reference notes