Empathy may be defined as the ability to share and/or understand others' emotional state. It is a multi-faceted construct that relies on discrete psychological processes with specific neural correlates. These psychological processes might be impaired in some mental disorders, such as schizophrenia, autism spectrum disorders, borderline personality disorder or mood disorders. Among these disorders, psychopathy is mainly characterized by a lack of empathy for others' distress associated with amygdala hypo-reactivity. In the context of doctor-patient relationships, clinical empathy also encompasses the physician's ability to communicate his or her understanding of the emotional state of the patient. However, sharing the emotional states may elicit compassion fatigue and burnout symptoms among physicians and medical students and reduce their empathic capacities. A decline of these capacities is indeed observed during medical training. Perspective-taking may protect physicians from such negative effects while allowing them to show sustained empathic concern. Interventions to promote empathy among medical students should target both communication skills and humanist values: communication skill may depend on humanist values to grow.