Alprazolam is the product of the incorporation of the triazolo ring into the benzodiazepine structure. More than 90% of alprazolam is absorbed after an oral dose; the absorption rate is dose independent. After a single oral dose of 0.5 to 3 mg of alprazolam, peak plasma concentrations of 7 to 40 ng/ml are reached at 0.7 to 2.1 hours after administration. Factors such as liver and kidney disease, smoking, age, sex, and obesity have minimal effects on alprazolam pharmacokinetics. A review of alprazolam-drug interactions revealed few that were clinically significant, except that cimetidine and oral contraceptives reduce alprazolam clearance and increase its half-life. The mechanisms of action of alprazolam are reviewed. Its anxiolytic effect is similar to that of other benzodiazepines, but the basis of its other effects is less clear. Like other benzodiazepines, it has a good ratio of efficacy to side effects; its most common side effect, mild sedation, occurs early in treatment. The potential of dependence to and abuse of alprazolam and its toxicity are similar to that of other benzodiazepines. Finally, alprazolam's therapeutic role as an anxiolytic and anti-depressant and its use in the management of panic attacks, agoraphobia, schizophrenia, cancer, the premenstrual syndrome, and anxiety and as a cardioprotective agent are assessed.