To compare the anxiolytic effects of mexazolam with those of alprazolam in patients with generalised anxiety disorder (GAD). Multicentre, randomised, double-blind, parallel-group clinical trial in 64 outpatients with GAD (DSM-IV criteria). Patients were assigned to mexazolam 1mg three times daily (n = 32) or alprazolam 0.5mg three times daily (n = 32) during 1 week, followed sequentially by a period of 2 weeks of reducing dosage according to therapeutic response and by 1-week taper and 1-week treatment-free periods. The Hamilton Anxiety Rating Scale (HAM-A), the Clinical Global Impression (CGI), and the Snaith & Zigmund anxiety and depression self-rating scale (SZS) were used to evaluate the patient’s clinical status. Both treatment groups showed a statistically significant anxiolytic effect: a decrease of mean HAM-A score of 16.28 with mexazolam (p < 0.0001 vs baseline) and 14.2 with alprazolam (p < 0.0001) and a reduction in CGI-disease severity score of 2.66 (p < 0.0001) with mexazolam and 2.44 with alprazolam (p < 0.0001). Although a higher absolute rate of responders was observed in the mexazolam group, there were no statistically significant differences in the between-group comparisons (80% vs 70% in HAM-A and 96.7% vs 86.7% in CGI evaluations). Five mexazolam and nine alprazolam recipients reported mild adverse events. Both mexazolam and alprazolam showed a significant anxiolytic effect and were well tolerated in the treatment of GAD, making it an effective pharmacotherapeutic alternative in the treatment of GAD.