Lysergic acid diethylamide (LSD) is used in Switzerland in the treatment of patients both in the context of compassionate use and in clinical studies including patients with anxiety associated with life-threatening diseases. Placebo-controlled, double-blind, cross-over studies using oral administration of 100 and 200 µg LSD were also conducted to better define the acute subjective, emotional, endocrine, and pharmacokinetic effects of LSD in healthy subjects. A study directly comparing the acute effects of LSD with those of MDMA and d-amphetamine has also recently been completed. LSD produced feelings of trust, closeness to others, and enhanced emotional empathy. LSD impaired the recognition of sad and fearful faces and reduced reactivity of the left amygdala relative to placebo during the presentation of fearful faces. These effects of LSD on emotion processing and sociality may be useful for LSD-assisted treatment of anxiety in patients with cancer. In this presentation I will present the current state of research in humans and the phenomenology of the acute effects of LSD in an experimental setting and evaluate aspects that could facilitate psychotherapy in a therapeutic setting in patients with anxiety or depression.