Anesthesia machine have envolved from simple ,pneumatic device to sophisticated, computer-based, fully integrated anesthesia systems.Understanding of modern anesthesia machines is essential for the safe practice of anesthesia . The traditional pneumatic machine has envolved into a complex electrical,mechanical and pneumatic multicomponent workstation.An anesthesia workstation integrates most of the components necessary for administrationof anesthesia in one unit.It consists of the anesthesia machine,vaporizers,ventilator,breathing system,scavenging system and monitors.Monitoring and control functions as well as alarms can be integrated . A checkout procedure is mandatory to determine whether equipment is functioning properly and ready for use or not. Properly checking equipment can reduce equipment related morbidity and mortality, improve preventive maintenance and educate the anesthesiologist about the equipment.