This is a very difficult medical ninjutsu and as such the success rate of this type of treatment isn't very high. Teamwork between the users is more important than anything else for a successful treatment.
To begin a large, square seal is drawn on the floor and the patient is placed at the centre. Four medical-nin sit at the corners and one at the head to lead the operation. A portion of an injured individual's body is used as a medium, and its cells are converted to regenerate a missing section of the body. As an agglomeration of cells, even hair is a useful medium. As the medium is converted the missing section of the body is filled up with new cells. Controlling the chakra into matching the proportion of cells is extremely hard, so the treatment requires extended periods of time. The medical-nin on hand actually have to trade places after tiring, indicating just how long it takes.
In the anime, it was shown that the technique can be performed by a single person. During the operation, the square seal and the medium coming from the injured person are not needed. Instead, four formula-lines are used to restore the missing section of the body. The technique is still very chakra-taxing, seen as Sakura Haruno fainted after using almost all of her chakra during the operation.