The constantly extending indication spectrum of magnetic resonance imaging (MRI) is a challenge for the anaesthesiologist, who is being increasingly more consulted for assistance during the examination. Due to the special technology of MRI the anaesthetic technique differs substantially from that in the operating theatre. In addition to the permanent strong magnetic field the intermittently used high frequency impulses are also a potential danger for the patient. Patients with metal implants (e.g. cardiac pacemaker) are particularly at risk. For the safe treatment of patients during MRI a special MRI compatible anaesthesia equipment is necessary. Unsuitable devices can lead to malfunctioning or to projectile effects (attracting ferromagnetic objects into the magnet) causing injury to the patients. This paper describes the MRI technology and the associated dangers for the patient as well as the characteristics of the anaesthetic techniques.