Infusion pumps incorporating 'Diprifusor' for the administration of propofol by target controlled infusion are now commercially available and are becoming more widely used. This paper considers possible future applications of target controlled infusion and summarises results obtained using prototype systems as a component of other control techniques and with other drugs. These include studies with patient-controlled systems for the administration of analgesia or sedation and a closed loop control system for the administration of propofol. Among currently available analgesic drugs, alfentanil and remifentanil are considered to be the most suitable for administration by target controlled infusion, but commercial systems for these agents are not yet available.