According to the definition given by the Legislative Decree n. 46 of 1997, medical device means any instrument, apparatus, appliance, material or other article, whether used alone or in combination (including the software used for a correct functioning).

intended by its manufacture to be used for human beings for the purpose of diagnosis, prevention, monitoring, treatment or alleviation of disease; diagnosis, monitoring, treatment, alleviation or compensation for an injury or handicap; investigation, replacement or modification of the anatomy of a physiological process; control conception, and which does not achieve its principal intended action in or on the human body by pharmacological, immunological or metabolic means, but which may be assisted in its function by such means. Medical devices are classified in four classes in function of their complexity and growing risk.

• Class I :
  Less critical devices, as the majority of the non invasive and non active ones (class I devices are divided in two other  underclass devices:  Class I sterile (those provided in a sterile status) and class I m (those that carry out a measuring function).
• Class IIa:
  Medium risk devices,  as are some non active devices (invasive and non) and active devices that interact with the human body not in a dangerous way.
• Class IIb:
  Medium/high risk devices, as are some non active devices (invasive ones) and active devices which interact with the human body in a dangerous way.
• Class III :
  High risk devices, as the majority of the implantable ones, containing medicines or products of animal origin and some devices that interact with the functions of vital organs.