Medical-nin are ninja who specialise in medical treatment and use of medical-oriented techniques to heal others. Becoming a medical ninja-nin requires high intelligence and excellent chakra control. A medical-nin is trained to avoid getting injured in any way, for the reason that if they are injured, then there would be nobody to heal the other members of their team. Medical-nin accompany other ninja on high ranking missions to increase the success rate of the mission and overall survival rate of the squad.
Medical-nin make use of the Mystical Palm Technique - a technique used to heal comrades and can also be used in surgery. It allows them to make precise incisions and then doubles as a means to heal a wound. For more serious injuries, multiple medical-nin can combine their efforts with techniques such as the Healing Resuscitation Regeneration Technique, which uses a portion of the patient's own body as a medium to help the healing process.
The knowledge of a medical-nin can be used for a variety of purposes; for example, Hana Inuzuka is a veterinarian medical-nin that specialises in the treatment of ninken. Chiyo, in the past, used her medicinal knowledge to create deadly poisons. However, her efforts were often counteracted by Tsunade, renowned as the greatest medical-nin in the world.
Field medical-nin (Konoha ones at least), when in the field of on the battlefield, are equipped with medical pouches in order to carry medical supplies as well as their regular weapons.
According to Madara Uchiha, the First Hokage, Hashirama Senju, was also able to use medical ninjutsu with such skill that he could heal himself instantly without the need of performing hand seals; Madara included that Tsunade, who is heralded as the greatest medical-nin in the world, pales in comparison - something Tsunade initially herself admits - but after seeing her Ninja Art Creation Rebirth - Strength of a Hundred Technique, Madara deemed Tsunade's healing abilities similar to that of her grandfather's.