Generalized Anxiety Disorder (GAD) is among the most common psychiatric disorders. It is characterized by persistent worry and apprehensiveness that manifests in a range of symptoms. However, current treatments are often ineffective or have intolerable side effects. We evaluated the safety, tolerability, and efficacy of MM-120 in patients with GAD. In this study, 198 adults with GAD and moderate-to-severe anxiety (HAM-A score ≥20) were randomized 1:1:1:1:1 to receive one dose of MM-120 at 25µg (n=39), 50µg (n=40), 100µg (n=40), or 200µg (n=40), or placebo (n=39). The primary objective was to assess the dose-response of MM-120 on HAM-A total score. Secondary endpoints included other efficacy measures, quality of life, and safety and tolerability. Both the 100µg and 200µg of MM-120 demonstrated clinically and statistically significant efficacy. The 100µg dose achieved the highest clinical activity with a significant reduction of 7.6 points in HAM-A total score compared to placebo at week 4 (-21.34 vs -13.75; P=0.0004). On Day 2, CGI-S scores showed a significant improvement of 1.8 points with 100µg versus 0.7 with placebo (P=0.0001). At week 4, 77.5% of subjects treated with 100µg showed a ≥50% improvement in HAM-A vs 30.77% with placebo; 50% achieved remission. Treatment-emergent adverse events occurred in 97.5% of participants treated with 100µg versus 56.4% with placebo. Most events were mild-to-moderate, occurred on dosing day, and consistent with the expected acute effects of MM-120. These findings suggest a rapid, robust, and durable clinical response to MM-120 in patients with GAD. Mind Medicine, Inc supported this study.