Alprazolam (Xanax) is a fairly new, yet very popular benzodiazepine tranquilizer. In 1985, it was 6th on a nationwide list of drugs mentioned in emergency room drug poisonings. A procedure was developed that allows alprazolam and its main urinary metabolites, alpha-hydroxyalprazolam and 3-hydroxymethyl-5-methyltriazolyl chlorobenzophenone, to be detected in urine specimens. A dual capillary column, dual nitrogen detector gas chromatographic system was used for reliable identification. Improved chromatographic performance was obtained by acetylating the metabolites. Method characteristics such as linearity, reproducibility, limit of detection, and recovery were determined. The method was tested by assaying urine specimens from hospitalized patients who had been ingesting alprazolam. In most cases, alpha-hydroxyalprazolam was found in the highest concentration and separated best from endogenous urine substances. A single dose concentration-time study was performed, and the time course of alprazolam and metabolite concentrations over 48 hours was determined.