Clonazepam has recently been approved for the treatment of panic disorder. Two large placebo-controlled efficacy trials were completed; superior benefit was found for the drug on most measures. The studies are reviewed in relation to the criteria set forth by Shear and Maser with respect to design, diagnostic, and outcome measures. Most, but not all, recommended measures were used. Measurement of panic attack severity, duration, and frequency were generally the least satisfactory of all outcome variables and failed to provide the consistent benefit that was found with other measures. A slow discontinuation phase was employed, and a benign withdrawal course was noted, although withdrawal from higher doses was associated with more emergent symptomatology.