A double-blind trial was undertaken to compare the antidepressant efficacy and the side effects of Lofepramine with those of Amitriptyline in the treatment of endogenous depression. The study involves 22 acutely ill endogenously depressive patients. 11 patients were treated with Lofepramine and the remaining 11 with Amitriptyline. The results demonstrate that both substances are effective in the treatment of depression. However, the therapeutical efficacy of Lofepramine is significantly greater than that of Amitriptyline. Furthermore, the tolerance of Lofepramine is better than that of Amitriptyline, and the side effects of Amitriptyline, especially in blood pressure dysregulation, are greater than those of Lofepramine.